Class 8 Science Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures (New Course)

Key Concept: Metals, Non-metals, Metalloids

c) Metalloid due to intermediate properties
[Solution Description]
Elements with properties intermediate between metals and non-metals are called metalloids. Since element X shows mixed conductivity and is solid at room temperature, it fits the definition of a metalloid.
Step-by-step explanation:
1. Metals are good conductors (e.g., copper), while non-metals are poor conductors.
2. Element X conducts electricity but not as well as copper, placing it between metals and non-metals.
3. It is solid at room temperature, unlike many non-metals (e.g., oxygen).
4. Therefore, X must be a metalloid like silicon or boron.

Key Concept: Types of Pure Substances

c) Water is a compound made up of hydrogen and oxygen elements
[Solution Description]
The decomposition of water ($H_2O$) into hydrogen ($H_2$) and oxygen ($O_2$) upon passing electricity indicates that water is a compound, not an element, as it can be broken down into simpler substances.

Key Concept: Pure Substances

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that water ($H_2O$) is a pure substance because it has a fixed composition of hydrogen and oxygen atoms. This is true because compounds like water are pure substances as they have a definite chemical composition and properties distinct from their constituent elements.
The reason states that pure substances cannot be separated into simpler substances by physical methods. This is also true since pure substances, whether elements or compounds, can only be broken down into simpler substances via chemical methods, not physical ones.
Moreover, the reason correctly explains the assertion because the fixed ratio of atoms in water (a compound) makes it a pure substance, which aligns with the definition given in the reason. Hence, both assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Pure Substances, Mixtures

b) Mixture due to the presence of multiple substances
[Solution Description]
A pure substance consists of only one type of particle (element or compound). Since the sample contains both sugar (a compound) and starch (another compound), it is a mixture.
Step-by-step explanation:
1. Pure sugar should contain only sucrose molecules ($C_{12}H_{22}O_{11}$).
2. Starch is a different compound ($(C_6H_{10}O_5)_n$).
3. The presence of two distinct compounds makes it a mixture.
4. Even small traces of impurity disqualify it as a pure substance.

Key Concept: Activity 8.3 Inference

c) Water is a pure substance composed of hydrogen and oxygen
[Solution Description]
In Activity 8.3, passing electric current through water breaks it down into hydrogen and oxygen, showing that water is composed of these two elements and thus is a compound.

Key Concept: Elements and Compounds, Physical and Chemical Changes

c) Chemical change because new substances with different properties are formed
[Solution Description]
Passing electric current through water causes a chemical reaction where water molecules break down into hydrogen and oxygen gases. This is an irreversible process where new substances with different properties are formed. Hence, it is a chemical change.
Step-by-step explanation:
1. Water ($H_2O$) is a compound.
2. Electric current provides energy to break the bonds between hydrogen and oxygen atoms.
3. New substances—hydrogen gas ($H_2$) and oxygen gas ($O_2$)—are formed.
4. These gases have properties different from water, confirming a chemical change.

Key Concept: Pure Substance Definition

b) A substance composed of only one type of particle, either element or compound
[Solution Description]
A pure substance is defined as a kind of matter that cannot be separated into other kinds of matter by any physical process. It consists of the same type of particles and can be either an element or a compound.

Key Concept: Pure Substances and Elements

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that water is a pure substance. This is true because, in science, a pure substance consists of the same type of particles. The reason states that pure substances consist of the same type of particles and cannot be separated into other kinds of matter by any physical process. This is also true, but it does not explain why water specifically is a pure substance. Water is considered a compound, which is a type of pure substance, but the reason only defines pure substances in general and does not link directly to water. Therefore, both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

Key Concept: Pure Substances, Elements, Compounds

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion states that breaking water into hydrogen and oxygen by passing an electric current is a physical change. However, this process is actually a chemical change because the chemical composition of water ($H_2O$) changes into hydrogen ($H_2$) and oxygen ($O_2$). The Reason states that a physical change involves the rearrangement of particles without altering their chemical composition, which is correct but does not explain the Assertion correctly since the given process is not a physical change. Therefore, Assertion is false, but Reason is true.

Key Concept: Definition of Pure Substances

b) A substance composed of only one type of particle and cannot be separated further by physical processes
[Solution Description]
A pure substance in science consists of the same type of particles and cannot be separated into other kinds of matter by any physical process. It differs from common usage where “pure” means unadulterated.

Key Concept: Elements and Compounds

c) Elements consist of atoms that are different from those of any other element
[Solution Description]
Elements are pure substances consisting of identical atoms and cannot be broken down into simpler substances by chemical methods. They are the building blocks of all matter, whereas compounds are formed by the chemical combination of elements.

Key Concept: Elements vs. Compounds

d) Elements cannot be broken down further, while compounds are made of two or more elements
[Solution Description]
An element is the simplest substance that cannot be broken down further into simpler substances. A compound is made up of two or more elements chemically combined in a fixed ratio and has properties different from its constituent elements.

Key Concept: Reaction of Iron Sulfide

c) Iron chloride and hydrogen sulfide.
[Solution Description]
According to the reaction given:
$Iron\ sulfide + Dilute\ Hydrochloric\ acid \rightarrow Iron\ chloride + Hydrogen\ sulfide$

Key Concept: Chemical Reactions

c) Hydrogen sulfide
[Solution Description]
The reaction between iron sulfide and dilute hydrochloric acid produces iron chloride and hydrogen sulfide gas. Hydrogen sulfide is known for its rotten egg-like odor.

Key Concept: Graphene Aerogel Properties and Applications

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that graphene aerogel is suitable for cleaning oil spills because of its high porosity and absorption capacity. This is true as the material’s lightweight and highly porous nature enables it to absorb liquids like oil efficiently. The reason explains that the porous structure of graphene aerogel permits it to absorb large volumes of liquids, which directly supports the assertion by detailing why this property makes it effective for environmental cleanup, such as oil spill remediation.

Key Concept: Alloys, Material properties

c) It is more resistant to corrosion and stronger than pure iron.
[Solution Description]
Stainless steel is preferred over pure iron because it has enhanced properties due to the addition of chromium and carbon. Chromium forms a protective oxide layer that prevents rusting, making it more durable in harsh environments. Carbon increases hardness and strength, improving its structural integrity. These combined properties make stainless steel resistant to corrosion and mechanically stronger than pure iron, ideal for construction.
Thus, stainless steel’s resistance to corrosion and superior mechanical strength are key reasons for its preference.

Key Concept: Application of Compounds and Mixtures

c) It is stronger and more durable than pure iron.
[Solution Description]
The syllabus explains that stainless steel is an alloy that is stronger and more durable than pure iron, which is why it is preferred for construction.

Key Concept: Graphene Aerogel Properties

b) It has a high absorbing capacity due to its porosity
[Solution Description]
Graphene aerogel is highly porous, which gives it a high absorbing capacity. This property allows it to absorb large amounts of substances like oil, making it effective for cleaning oil spills.

Key Concept: Innovations: Creation of materials with special properties

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that graphene aerogel can be used to clean up oil spills because of its high absorbing capacity. This is true as graphene aerogel’s porous structure allows it to absorb liquids efficiently. The reason given is that graphene aerogel is highly porous, contributing to its absorption capability. This is also true and correctly explains why the assertion is valid. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Chemical reactions, Compounds

d) Hydrogen sulfide
[Solution Description]
Referencing the given chemical equation: Iron sulfide ($FeS$) reacts with dilute hydrochloric acid ($HCl$) to form iron chloride ($FeCl_2$) and hydrogen sulfide ($H_2S$). The equation clearly shows that hydrogen sulfide is the gaseous product formed during this reaction.
Hence, the gas produced is hydrogen sulfide.

Key Concept: Properties of Graphene Aerogel

b) It is highly porous with high absorbing capacity.
[Solution Description]
The syllabus states that graphene aerogel is highly porous and has a high absorbing capacity, making it useful for cleaning up oil spills.

Key Concept: Assertion-Reason

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that graphene aerogel is the lightest material on earth, which is true as mentioned in the syllabus. The reason given is that graphene aerogel is highly porous and has a high absorbing capacity, which is also true. However, the porosity and absorbing capacity are properties of graphene aerogel but do not directly explain why it is the lightest material. Therefore, both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

Key Concept: Graphene aerogel properties, Environmental applications

b) 500 kg
[Solution Description]
First, convert the mass of graphene aerogel from kilograms to grams: $5 \text{ kg} = 5000 \text{ g}$. Next, calculate the total oil absorption using the given ratio: $5000 \text{ g} \times 100 = 500000 \text{ g}$. Convert grams back to kilograms: $500000 \text{ g} = 500 \text{ kg}$.
Therefore, a 5 kg block of graphene aerogel can absorb 500 kg of oil.

Key Concept: Alloys and Mixtures

b) It is a mixture of iron with other elements like chromium and carbon
[Solution Description]
Stainless steel is an alloy made by mixing iron with other elements like chromium and carbon. This combination enhances its strength and durability compared to pure iron.

Key Concept: States of Elements

b) Mercury
[Solution Description]
Most elements are solids at room temperature. However, mercury (a metal) and bromine (a non-metal) are liquids. Among the options, **mercury** is the correct answer.

Key Concept: States of Elements, Classification of Elements

c) Mercury and bromine
[Solution Description]
The only two elements that exist as liquids at room temperature are mercury (a metal) and bromine (a non-metal). This is explicitly mentioned in the syllabus under “Snapshots.”

Key Concept: Classification of Elements

c) Silicon (Si)
[Solution Description]
Metalloids exhibit properties intermediate between metals and non-metals. Silicon (Si) is classified as a metalloid, while gold (Au) is a metal and sulfur (S) is a non-metal.

Key Concept: Classification of Elements

c) Silver
[Solution Description]
Elements can be metals or non-metals. Gold, silver, and iron are metals, whereas sulfur is a non-metal. Among the options, **silver** is a metal.

Key Concept: Basic Definition

d) Gold
[Solution Description]
An element is a pure substance that cannot be broken down into simpler substances. Examples include hydrogen, oxygen, gold, and sulfur. Among the options, only **gold** fits this definition. Water and carbon dioxide are compounds, while air is a mixture.

Key Concept: States of Elements at Room Temperature

b) Bromine (Br)
[Solution Description]
The correct answer can be determined by recalling the states of elements at room temperature. From the syllabus, only mercury (Hg, metal) and bromine (Br, non-metal) are liquids at room temperature. The other options are either solids or gases.

Key Concept: Elements, Classification of Elements

c) Assertion is true, but Reason is false.
[Solution Description]
The Assertion states that all elements that exist as gases at room temperature are non-metals. From the syllabus, we know that 11 elements exist in a gaseous state at room temperature, and all of them are non-metals like oxygen, helium, nitrogen, etc. Thus, the Assertion is true. The Reason claims that the ability to exist in gaseous state at room temperature is a property exhibited only by non-metallic elements. However, while it is true for known elements currently, this is not an inherent or exclusive property of non-metals, as metals can also exist in gaseous states under different conditions (though not at room temperature). Therefore, the Reason is false because it generalizes a condition that is circumstantial rather than fundamental. Hence, the correct option is (c).

Key Concept: Elements, Metalloids

c) Silicon
[Solution Description]
Silicon and boron are metalloids, which have properties intermediate between metals and non-metals. This is stated in the syllabus under “A step further.”

Key Concept: Molecules of Elements

c) O\_2
[Solution Description]
The syllabus specifies that atoms of most elements combine to form molecules. For oxygen, two oxygen atoms combine to form the diatomic molecule $O_2$. Therefore, the correct answer is $O_2$.

Key Concept: Assertion-Reason

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
Gold is a pure substance and classified as an element because it consists of identical gold atoms (Au). According to the definition of elements, they cannot be broken down into simpler substances by chemical reactions. Thus, both Assertion (A) and Reason (R) are true. Moreover, Reason (R) correctly explains why gold is an element, as the inability to break it down further chemically is the defining characteristic of an element.

Key Concept: Elements and their states at room temperature

c) Assertion is true, but Reason is false.
[Solution Description]
Assertion (A): Bromine is indeed a liquid element at room temperature, as mentioned in the syllabus. This makes the assertion true.
Reason (R): The syllabus states that bromine is one of the two elements (along with mercury) that are liquid at room temperature. However, bromine is not the only non-metal in this state because mercury is a metal. This means the reason is false.
Therefore, the correct answer is: Assertion is true, but Reason is false.

Key Concept: Elements vs. Compounds, Classification of Elements

d) $\text{H}_2$ and $\text{O}_2$ are elements, and $\text{H}_2\text{O}$ is a compound.
[Solution Description]
Hydrogen ($\text{H}_2$) and oxygen ($\text{O}_2$) are elements because they consist of identical atoms and cannot be broken down further by chemical means. Water ($\text{H}_2\text{O}$) is a compound formed by the chemical combination of these elements. Thus, $\text{H}_2$ and $\text{O}_2$ are elements, and $\text{H}_2\text{O}$ is a compound with fixed composition.

Key Concept: Pure Substances vs Mixtures

c) Baking soda
[Solution Description]
A pure substance consists of the same type of particles and cannot be separated into other substances by physical processes. Among the options, baking soda (sodium bicarbonate) is a compound with a fixed composition, making it a pure substance. Milk, packed fruit juice, and soil are mixtures as they contain multiple components.

Key Concept: Elements

c) A substance that cannot be broken down into simpler substances
[Solution Description]
An element is a pure substance that cannot be broken down into simpler substances by chemical means. It consists of identical atoms and serves as a fundamental building block of matter. Compounds, mixtures, and solutions do not fit this definition since they can be decomposed or separated further.

Key Concept: Pure Substances, Compounds, Elements

b) Mixture of elements
[Solution Description]
According to scientific definition, a pure substance consists of the same type of particles and cannot be separated into other kinds by any physical process. Since the sample contains both gold and silver atoms, it is not a pure substance but a mixture of elements.

Key Concept: Definition of Pure Substance

b) The same type of particles
[Solution Description]
A pure substance consists of the same type of particles. These particles behave identically and cannot be separated into other kinds of matter by any physical process.

Key Concept: Pure substances, chemical vs physical change

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
Water is a compound made of hydrogen and oxygen in a fixed ratio ($H_2O$). As a compound, it qualifies as a pure substance since it cannot be separated into its constituent elements by physical methods (e.g., filtration or distillation). On the other hand, passing electric current through water breaks the chemical bonds between hydrogen and oxygen, resulting in a chemical change where new substances ($H_2$ and $O_2$) are formed. Both statements are true, but the reason does not explain why water is a pure substance—it only describes a property of water under specific conditions.

Key Concept: Elements, Compounds, Minerals

c) Mineral that is a compound
[Solution Description]
The substance is naturally occurring, solid, and has a fixed chemical composition with two elements chemically combined. This matches the definition of a mineral that is a compound (not an element).

Key Concept: Examples of Pure Substances

c) Packed fruit juice
[Solution Description]
A pure substance cannot be separated into other substances by physical processes. Packed fruit juice contains multiple components like water, sugar, and flavorings, making it a mixture and not a pure substance.

Key Concept: Pure vs Impure Substances

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion states that milk is a pure substance in science because it cannot be separated into other substances by physical processes. However, milk is actually a mixture of water, fats, proteins, and other components, which can be separated by physical processes like centrifugation or filtration. Therefore, the Assertion is false.
The Reason correctly states the scientific definition of a pure substance—it consists of the same type of particles and cannot be broken down further by physical means. Hence, the Reason is true.
Since the Assertion is false but the Reason is true, the correct answer is option d).

Key Concept: Compounds, Pure Substances

a) Water has a fixed composition, whereas milk’s composition varies
[Solution Description]
Water ($H_2O$) is a compound made up of hydrogen and oxygen chemically combined in a fixed ratio, making it a pure substance. Milk, on the other hand, contains water, fats, proteins, and other substances, so it is a mixture.

Key Concept: Pure vs Impure Substance

b) Baking soda
[Solution Description]
A pure substance, as per science, consists of the same type of particles and cannot be separated into other substances by physical means. Elements and compounds are examples of pure substances. Among the given options, only baking soda (a compound) fits this definition.

Key Concept: Pure Substances

d) Assertion is false, but Reason is true.
[Solution Description]
The assertion states that milk is a pure substance, which is false because milk contains multiple substances like water, fats, proteins, etc. The reason states that a pure substance consists of the same type of particles, which is true as per the definition. Therefore, Assertion is false and Reason is true.

Key Concept: Classification of Pure Substances

c) Sugar
[Solution Description]
Elements are pure substances composed of identical atoms and cannot be broken down further. Sugar ($C_{12}H_{22}O_{11}$) is a compound, not an element, as it consists of carbon, hydrogen, and oxygen atoms chemically bonded. Gold (Au), sulfur (S), and oxygen (O$_2$) are all elements.

Key Concept: Mixtures and Their Uses

d) It is highly porous and can absorb large amounts of oil.
[Solution Description]
Graphene aerogel is known for being the lightest material on earth, with high porosity and absorption capacity. It can hold up to 900 times its weight in oil, making it useful for environmental cleanup.

Key Concept: Mixtures

c) Homogeneous mixture
[Solution Description]
Stainless steel is an alloy made by mixing iron with carbon and other metals like chromium and nickel to enhance its properties. It is not a pure element, compound, or heterogeneous mixture but a homogeneous mixture (alloy).

Key Concept: Dhokra Art, Alloys

c) Alloys like brass and bronze enhance durability and aesthetic appeal
[Solution Description]
Brass and bronze are alloys, which have better mechanical properties (such as strength and durability) compared to pure metals. These alloys provide the shiny golden appearance and sturdiness required for Dhokra art.

Key Concept: Air Composition, Compounds vs. Mixtures

d) Air is a heterogeneous mixture of gases that can be physically separated
[Solution Description]
Air is a mixture of gases (like nitrogen, oxygen, and carbon dioxide) that retain their individual properties and can be separated by physical means, unlike compounds where elements are chemically bonded.

Key Concept: Elements and Compounds

c) Water
[Solution Description]
A compound is formed when two or more elements chemically combine in fixed proportions. Water ($H_2O$) is a compound consisting of hydrogen and oxygen, while nitrogen, iron, and air are either elements or mixtures.

Key Concept: Elements, Compounds, Mixtures

d) Assertion is false, but Reason is true.
[Solution Description]
Graphene aerogel is not a compound; it is a form of carbon, which is an element. The assertion that graphene aerogel is a compound is false because compounds are formed by the chemical combination of two or more elements in a fixed proportion, whereas graphene aerogel consists only of carbon atoms arranged in a specific structure. The reason states that graphene aerogel has unique properties due to its carbon-based chemical structure, which is true—however, this does not explain why it is a compound (since it is not). Therefore, Assertion is false, but Reason is true.

Key Concept: Elements and Compounds

c) Carbon dioxide
[Solution Description]
A compound is a substance formed when two or more elements are chemically bonded together. Water ($H_2O$) consists of hydrogen and oxygen atoms chemically combined, making it a compound.

Key Concept: Alloys and Applications

d) It is stronger and more durable than pure iron.
[Solution Description]
Stainless steel is an alloy made by combining iron with chromium and sometimes other metals. It is stronger, more durable, and resistant to rust compared to pure iron, making it ideal for construction.

Key Concept: Elements, Compounds, Mixtures

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
Water ($H_2O$) is indeed a compound as it consists of hydrogen and oxygen atoms chemically bonded in a fixed ratio of 2:1. The reason correctly defines a compound as a substance formed by the chemical combination of elements in fixed proportions. Hence, both the assertion and reason are true, and the reason accurately explains the assertion.

Key Concept: Graphene Aerogel, Properties of Mixtures

c) Its high porosity allows efficient absorption of oil
[Solution Description]
Graphene aerogel is highly porous and has a high absorbing capacity, making it capable of soaking up large amounts of oil from spills. It is also extremely light, so it can float on water and be easily deployed.

Key Concept: Applications of Elements and Compounds

c) Brass or bronze
[Solution Description]
Dhokra art involves using molten brass (an alloy of copper and zinc) or bronze (an alloy of copper and tin) to fill moulds after wax is melted out. These alloys give the art its characteristic shiny golden colour.

Key Concept: Elements, Compounds, and Mixtures

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that graphene aerogel is used as an environmental cleaner because of its high absorbing capacity. This is true, as mentioned in the syllabus where it highlights its ability to clean up oil spills.
The reason given is that graphene aerogel is highly porous and made from carbon, making it the lightest material on earth. This is also true as per the syllabus.
However, while the reason provides properties of graphene aerogel, it does not directly explain why it is used as an environmental cleaner. The high porosity leads to high absorption, but this connection is not explicitly stated in the reason. Therefore, both statements are true, but the reason is not the correct explanation of the assertion.

Key Concept: Composition of air

c) Nitrogen
[Solution Description]
Air is a mixture composed mainly of nitrogen, oxygen, argon, carbon dioxide, and water vapor. According to the syllabus, nitrogen makes up about 78\% of the air, which is the highest among all the components. Oxygen follows at approximately 21\%, while the remaining gases constitute a very small fraction. Therefore, nitrogen is the correct answer.

Key Concept: Air composition, lime water test

c) The solution remains colorless
[Solution Description]
The lime water test is specific to carbon dioxide. Nitrogen gas does not react with calcium hydroxide (lime water), so no milky appearance will be observed. The solution remains colorless.

Key Concept: Assertion-Reason

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion states that air is a uniform mixture with varying composition, which is incorrect because uniform mixtures have consistent composition throughout. The Reason claims that nitrogen and oxygen are chemically combined in fixed proportions, which is false as they exist as separate molecules without forming chemical bonds. Thus, both Assertion and Reason are false, but only the Reason’s falsity is relevant here as it contradicts the concept of mixtures.

Key Concept: Assertion-Reason

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that air is a uniform mixture, which is true because the components of air (nitrogen, oxygen, argon, carbon dioxide, etc.) are evenly distributed throughout. The Reason explains that these components retain their individual properties and are uniformly mixed, which correctly justifies why air is classified as a uniform mixture. Therefore, both Assertion and Reason are true, and the Reason is the correct explanation for the Assertion.

Key Concept: Combustion, oxygen requirement

c) The flame extinguishes immediately
[Solution Description]
Combustion requires oxygen. Since nitrogen gas does not support combustion, the flame will extinguish immediately due to lack of oxygen.

Key Concept: Dust Particles in Air

b) Dust particles
[Solution Description]
The tiny particles observed in a beam of sunlight are dust particles suspended in the air. These particles are not part of the air’s natural composition and are considered pollutants.

Key Concept: Reaction of Lime Water

c) Due to the presence of carbon dioxide
[Solution Description]
Lime water turns milky because carbon dioxide in the air reacts with calcium hydroxide in lime water to form calcium carbonate, which is insoluble and appears as a white precipitate. The reaction is:
$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$.

Key Concept: Composition of Air

d) Nitrogen
[Solution Description]
The main component of air is nitrogen, which constitutes about 78\% of the air by volume. Oxygen is the second most abundant gas, making up about 21\% of the air.

Key Concept: Nature of air

c) Its components retain their individual properties.
[Solution Description]
A mixture is formed when two or more substances are mixed without undergoing any chemical change. Air consists of various gases like nitrogen, oxygen, and carbon dioxide that retain their individual properties and do not chemically combine. Hence, air is classified as a mixture, specifically a uniform (homogeneous) mixture, because its composition is consistent throughout.

Key Concept: Particulate matter, air pollutants

c) Air consists of both gases and suspended solid particles
[Solution Description]
The presence of tiny particles on the black sheet indicates that air contains suspended particulate matter (dust, soot). These are not part of the gaseous composition but are pollutants suspended in air.

Key Concept: Reaction of lime water with air

d) Carbon dioxide
[Solution Description]
Lime water ($Ca(OH)_2$) reacts with carbon dioxide ($CO_2$) present in the air to form calcium carbonate ($CaCO_3$), which is insoluble and appears as a milky solution. The reaction is given by:
$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$.
Thus, the milky appearance confirms the presence of carbon dioxide in the air.

Key Concept: Assertion-Reason

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
Air is composed of various gases like nitrogen, oxygen, carbon dioxide, and other trace gases. These gases are mixed uniformly but do not undergo any chemical reaction to form a new substance. Each gas retains its own properties, and they can be separated through physical processes such as fractional distillation. Therefore, both the Assertion and Reason are true, and the Reason correctly explains why air is considered a mixture.

Key Concept: Native Minerals

d) Sulfur
[Solution Description]
Native minerals are pure elements and can be metals or non-metals. Sulfur is a native non-metal mineral, while gold and silver are native metals.

Key Concept: Uses of Minerals

c) Calcite
[Solution Description]
The syllabus states that cement is made from calcite, quartz, alumina, and iron oxide. Among the options, calcite is explicitly mentioned as one of them.

Key Concept: Examples of Minerals

d) Talc
[Solution Description]
Talcum powder is made from the mineral talc. From the syllabus, it is explicitly mentioned that talc is the mineral used for this purpose.

Key Concept: Mineral Composition, Properties

d) The asymmetric arrangement of silicon and oxygen atoms generates charge imbalance under stress
[Solution Description]
Quartz’s piezoelectric property arises from its crystalline structure composed of silicon and oxygen ($SiO_2$). When mechanical stress is applied, the arrangement of these atoms generates an electric charge. This unique property makes it useful in precision timing devices like watches.

Key Concept: Comparative Mineralogy, Native Minerals

c) Gold and talc
[Solution Description]
Native minerals are pure elements like gold (Au) or sulfur (S), whereas compound minerals consist of multiple elements (e.g., talc ($Mg_3Si_4O_{10}(OH)_2$)). Gold is a native metal while talc is a hydrated magnesium silicate compound.

Key Concept: Assertion-Reason

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description] The Assertion states that quartz is composed of silicon and oxygen, which is true as per the syllabus. The Reason provides its chemical formula ($SiO_2$), confirming that it consists of silicon and oxygen atoms, making the Reason both true and a correct explanation for the Assertion.

Key Concept: Chemical Composition of Minerals

c) Compounds made up of more than one element
[Solution Description]
According to the syllabus, most minerals are compounds made up of more than one element, although some can be pure elements (native minerals).

Key Concept: Chemical Composition of Minerals

d) Talc
[Solution Description]
The mineral described here is talc, which has the chemical formula $Mg_3Si_4O_{10}(OH)_2$ and is known for its softness and use in talcum powder.

Key Concept: Native Minerals, Compound Minerals

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The Assertion states that gold is a native mineral because it occurs naturally in its pure form, which is correct based on the syllabus definition of native minerals as pure elements. The Reason claims that native minerals like gold and silver cannot be extracted through chemical processes because they are already in their elemental state. While the Reason is true, it incorrectly connects this fact to why gold is a native mineral. Gold being a native mineral is due to its natural occurrence in pure form, not because extraction isn’t needed. Thus, both statements are true, but the Reason does not correctly explain the Assertion.

Key Concept: Mineral Uses, Industrial Applications

b) Neutralizing acidic soils in agriculture
[Solution Description]
Calcite reacts with acids due to its carbonate composition ($CaCO_3 + 2H^+ \rightarrow Ca^{2+} + CO_2 + H_2O$). This neutralization reaction is a chemical property used in acid neutralization, unlike its physical uses in cement or chalk production.

Key Concept: Mineral Properties

c) High solubility in water
[Solution Description]
Mica is known for its layered structure and ability to split into thin sheets. It does not dissolve easily in water, so being highly soluble is not a property of mica.

Key Concept: Chemical Composition of Minerals

c) Assertion is true, but Reason is false.
[Solution Description]
The Assertion states that talc is composed of hydrated magnesium silicate, which is correct as its chemical formula is $Mg_3Si_4O_{10}(OH)_2$. The Reason correctly provides this formula but incorrectly links it to the use of talc in talcum powder. While the chemical composition is accurate, the usage in talcum powder is due to its softness and not directly because of its chemical formula.
Therefore, the Assertion is true, but the Reason is false because it misrepresents the causal relationship between the chemical formula and the usage of talc.

Key Concept: Water, Minerals

c) Calcium carbonate and magnesium carbonate
[Solution Description]
Water becomes alkaline when it contains substances that release hydroxide ions (OH$^-$) or accept hydrogen ions. Calcium carbonate (CaCO$_3$) and magnesium carbonate (MgCO$_3$), found in limestone areas, dissolve to form weakly basic solutions. Quartz is neutral, and iron sulfide would make water acidic by forming sulfuric acid. Sodium chloride is neutral and doesn’t affect pH.

Key Concept: Alloys

d) Stainless steel
[Solution Description]
Stainless steel is an alloy containing iron, nickel, chromium, and carbon. It is highly durable and resistant to rust, making it suitable for surgical instruments.

Key Concept: Minerals

c) Quartz
[Solution Description]
Quartz is a naturally occurring mineral widely used in the production of electronic components and glass due to its properties.

Key Concept: Alloys

c) Stainless steel
[Solution Description]
Stainless steel is widely used in surgical instruments because it contains iron, nickel, chromium, and carbon, which make it resistant to rust and corrosion.

Key Concept: Real-life applications of alloys

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that stainless steel is preferred for making surgical instruments due to its rust and corrosion resistance. This is true because stainless steel’s properties make it suitable for medical applications where hygiene and durability are critical. The Reason explains that the presence of chromium in stainless steel forms a protective oxide layer, which prevents rusting. This is also true and correctly explains why stainless steel is resistant to rust and corrosion. Therefore, both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Key Concept: Water

d) $H_2O$, ability to dissolve many substances
[Solution Description]
The chemical formula of water is $H_2O$. Its polar nature allows it to dissolve a wide variety of substances, making it a universal solvent.

Key Concept: Assertion-Reason

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that stainless steel is resistant to rust and corrosion due to the presence of chromium and nickel. This is true. The Reason explains that chromium forms a protective oxide layer on the surface, which prevents further oxidation, protecting the steel from rust and corrosion. Both statements are true, and the Reason correctly explains the Assertion.

Key Concept: Air

c) Nitrogen
[Solution Description]
Nitrogen makes up about 78\% of the Earth’s atmosphere. Due to its inert nature, nitrogen is often used in food packaging to displace oxygen, preventing oxidation and spoilage.

Key Concept: Alloys and Corrosion

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that stainless steel is preferred over pure iron for surgical instruments due to its corrosion resistance, which is true. The Reason explains that chromium in stainless steel forms a passive oxide layer, preventing further oxidation, which is also correct and directly explains why stainless steel resists corrosion. Hence, both the Assertion and Reason are true, and the Reason is the correct explanation of the Assertion.

Key Concept: Alloys, Minerals

c) Copper, chromium, and nickel
[Solution Description]
To create an alloy that is both corrosion-resistant and conductive, we need components that provide these properties. Copper provides excellent conductivity while chromium offers corrosion resistance (as seen in stainless steel). Nickel also enhances corrosion resistance. Zinc alone doesn’t provide enough corrosion resistance.
The best combination would be copper (good conductor) with chromium (corrosion resistance) and nickel (additional corrosion resistance), similar to some industrial alloys used in marine applications.

Key Concept: Air, Chemical Reactions

c) Solubility in water under pressure
[Solution Description]
Different gases can be separated based on their physical properties. Carbon dioxide dissolves in water under pressure (used in carbonated drinks), while nitrogen and oxygen have much lower solubility. This difference in solubility is commonly exploited in gas separation processes. Reactivity with acid or density differences wouldn’t be practical for large-scale separation, and thermal stability isn’t relevant here since all these gases are stable at normal temperatures.

Key Concept: Air

c) Oxygen
[Solution Description]
Oxygen constitutes about $21\%$ of the air and is vital for respiration in living organisms and supports combustion.

Key Concept: Minerals and Alloys

b) A mixture of two or more metals with distinct properties
[Solution Description]
Mishraloha is the name given to a mixture of two or more metals, which has properties distinct from its constituent metals. It was mentioned in ancient Indian texts like Charaka Samhita and Rasaratna Samucchaya for medicinal purposes.

Key Concept: Minerals, Alloys, Mishraloha

d) 3.75 grams
[Solution Description]
The traditional ratio of Kamsya is 4 parts Copper to 1 part Tin. Given 15 grams of Copper, we need to find the amount of Tin required.
Step 1: Determine the ratio factor.
$\text{Ratio of Copper} = 4 \, \text{parts}, \quad \text{Ratio of Tin} = 1 \, \text{part}$
Step 2: Calculate the scaling factor.
$15 \, \text{grams of Copper} \div 4 = 3.75 \, \text{grams per part}$
Step 3: Compute the required Tin.
$3.75 \, \text{grams/part} \times 1 \, \text{part} = 3.75 \, \text{grams of Tin}$
Thus, 3.75 grams of Tin must be added to 15 grams of Copper to make Kamsya.

Key Concept: Dhokra Art, Alloys

c) 200 grams
[Solution Description]
Brass is composed of 60\% Copper and 40\% Zinc by mass. To find the mass of Zinc required for 500 grams of brass:
Step 1: Identify the percentage composition.
$\text{Zinc percentage} = 40\%$
Step 2: Calculate the mass of Zinc.
$500 \, \text{grams} \times 0.40 = 200 \, \text{grams of Zinc}$
Therefore, 200 grams of Zinc are needed to prepare 500 grams of brass.

Key Concept: Alloy Composition

c) Copper and Tin
[Solution Description]
Bronze (Kamsya) is an alloy consisting of Copper ($Tamra$) and Tin ($Vanga$) in a ratio of 4 parts Copper to 1 part Tin, used for improving digestion and immunity.

Key Concept: Our scientific heritage

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The Assertion states that Bronze (Kamsya) was used for medicinal purposes in ancient India, which is true as per the syllabus mentioning its use to improve digestion and boost immunity. The Reason cites the Charaka Samhita and Susruta Samhita mentioning the use of alloys like Bronze for their distinct properties, which is also correct. However, while both statements are true, the Reason does not directly explain why Bronze was specifically used for medicinal purposes; it only explains the general use of alloys. Therefore, the Reason is not the correct explanation of the Assertion.

Key Concept: Concept: Minerals and Their Composition

c) A mixture of metals with distinct properties
[Solution Description]
Mishraloha is a mixture of two or more metals with properties distinct from its constituent metals, as described in ancient Indian texts. It was used for medicinal purposes.

Key Concept: Concept: Dhokra Art and Metal Usage

b) Brass or Bronze
[Solution Description]
Dhokra art involves making wax models coated with clay that are later replaced with molten brass or bronze to create durable, shiny golden-colored figures.

Key Concept: Concept: Use of Alloys in Ancient India

c) 4 parts Copper to 1 part Tin
[Solution Description]
According to ancient Indian texts, the alloy Bronze (Kamsya) was prepared using 4 parts Copper (\$Tamra\$) and 1 part Tin (\$Vanga\$).

Key Concept: Dhokra Art

b) Brass or Bronze
[Solution Description]
Dhokra art uses molten brass or bronze to fill the hollow clay mould after removing the beeswax model. This gives the art strength and a shiny golden appearance.

Key Concept: Minerals and Alloys

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that bronze is an alloy of copper and tin used in ancient India for medicinal purposes, which is true as per the syllabus. The reason explains that bronze was known to improve digestion and boost immunity, as mentioned in ancient Indian texts like Charaka Samhita, which is also correct. Moreover, the reason correctly explains the assertion by providing the specific benefits of bronze mentioned in historical texts.

Key Concept: Minerals, Mishraloha, Scientific Heritage

c) Bronze exhibits improved medicinal properties due to alloying
[Solution Description]
Bronze (Kamsya) is an alloy of Copper and Tin. Ancient texts highlight its medicinal benefits due to the synergistic effects of combining metals. Pure Copper may be too reactive or less effective in certain treatments, whereas the alloy’s properties enhance digestion and immunity.
Step 1: Understand the properties of pure Copper.
Pure Copper is highly conductive but may oxidize or react undesirably in medicinal applications.
Step 2: Analyze the alloy’s advantages.
The addition of Tin stabilizes the Copper, making it more suitable for therapeutic use while retaining beneficial properties.

Key Concept: Mineral Alloys and Ancient Indian Science

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that Bronze was used in ancient Indian medicine for enhancing physical healing properties, which is true as historical texts like Charaka Samhita mention its medicinal applications. The Reason explains that Bronze has antimicrobial properties due to its composition (Copper and Tin), which supports the Assertion since these properties directly contribute to healing and immunity enhancement. Therefore, both are true, and the Reason correctly explains the Assertion.

Key Concept: Nature of Compounds

c) Sugar is a compound made of carbon, hydrogen, and oxygen
[Solution Description]
Sugar decomposes upon heating to form simpler substances (carbon and water), which confirms that it is a compound. A compound consists of two or more elements chemically combined in a fixed ratio, unlike an element.

Key Concept: Conservation of mass, Chemical decomposition

c) Exactly 50 g
[Solution Description]
According to the Law of Conservation of Mass, the total mass of reactants equals the total mass of products in a closed system.
Since sugar decomposes into carbon and water (as per the reaction $C_{12}H_{22}O_{11} \rightarrow 12 C + 11 H_2O$), no mass is lost or gained.
Thus, total mass of products = 50 g.

Key Concept: Decomposition of Sugar

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion states that sugar is an element because it decomposes into simpler substances. However, elements are pure substances that cannot be broken down into simpler substances by chemical means, which makes the Assertion false. The Reason correctly states that elements cannot be broken down into simpler substances, which aligns with the definition of an element. Therefore, the Assertion is false, but the Reason is true.

Key Concept: Chemical Change Observation

b) Small droplets of water near the open end of the tube
[Solution Description]
During the heating of sugar, small droplets of water are observed inside the boiling tube near its open end. These droplets confirm the presence of water in the decomposition products.

Key Concept: Nature of Sugar

d) It is made up of multiple elements combined chemically
[Solution Description]
Sugar decomposes into carbon and water upon heating, which means it can be broken down into simpler substances. Elements cannot be broken down further by chemical means. Since sugar consists of carbon, hydrogen, and oxygen combined chemically, it is classified as a compound.

Key Concept: Observation during Decomposition

c) Water droplets appear inside the boiling tube near its open end
[Solution Description]
The boiling tube is being heated, so any moisture in the air would evaporate rather than condense. The appearance of water droplets near the open end indicates that they originate from the decomposition of sugar, as the reaction produces water vapor that condenses upon cooling.

Key Concept: Chemical properties, Pure substances

c) Because carbon is chemically different from sugar and undergoes direct combustion
[Solution Description]
The black residue is carbon, an element, while sugar is a compound (sucrose).
Carbon burns in air to form carbon dioxide ($C + O_2 \rightarrow CO_2$) with a clean flame, whereas sugar decomposes first then burns producing multiple products like carbon, water vapor, and other gases.
This difference arises because compounds have different chemical properties than their constituent elements.

Key Concept: Decomposition of sugar, Elements vs. Compounds

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the decomposition of sugar into carbon and water proves it is a compound. This is true because compounds can be broken down into simpler substances (elements or other compounds) by chemical changes like heating. The reason correctly explains that a compound can be decomposed into simpler substances chemically, whereas an element cannot. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Decomposition of Sugar

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that sugar decomposes into carbon and water when heated, which is true as observed in Activity 8.4. The Reason states that sugar is a compound composed of carbon, hydrogen, and oxygen, which is also true since the decomposition produces carbon and water (which contains hydrogen and oxygen). Furthermore, the Reason correctly explains why the Assertion occurs because the presence of these elements in sugar leads to its decomposition into carbon and water upon heating.

Key Concept: Decomposition of sugar, Elements vs Compounds

b) 42.1 g
[Solution Description]
The chemical formula for sugar (sucrose) is $C_{12}H_{22}O_{11}$.
First, calculate the molar mass of sucrose:
$M_{\text{sucrose}} = 12 \times 12 + 22 \times 1 + 11 \times 16 = 144 + 22 + 176 = 342$ g/mol.
On heating, sucrose decomposes as:
$C_{12}H_{22}O_{11} \rightarrow 12 C + 11 H_2O$
Molar mass ratio of carbon to sucrose:
$\frac{12 \times 12}{342} = \frac{144}{342} \approx 0.421$
For 100 g sucrose:
Mass of carbon = $100 \times 0.421 = 42.1$ g.

Key Concept: Decomposition of Sugar

d) Carbon and water
[Solution Description]
Heating sugar causes it to decompose into simpler substances: carbon and water. This is represented by the equation $\text{Sugar} \rightarrow \text{Carbon} + \text{Water}$. Thus, the correct answer must include both carbon and water as the decomposition products.

Key Concept: Decomposition of Sugar

a) Carbon and water
[Solution Description]
When sugar is heated, it decomposes into carbon and water. The reaction can be represented as: $\text{Sugar} \rightarrow \text{Carbon} + \text{Water}$. Water further consists of hydrogen and oxygen, but the key observation here is the formation of carbon and water.

Key Concept: Pure substances, Compounds vs. Mixtures

b) Because the solution contains multiple types of particles.
[Solution Description]
While sodium chloride and water are both pure substances (compounds), their combination forms a homogeneous mixture (solution). A pure substance must consist of a single type of particle, but the solution contains $Na^+$, $Cl^-$, and $H_2O$ molecules, making it a mixture.

Key Concept: Compounds and Elements

d) A compound
[Solution Description]
Sodium chloride (NaCl) is formed by the chemical combination of sodium (a metal) and chlorine (a gas) in a fixed 1:1 ratio. It has properties different from its constituent elements and cannot be separated into sodium and chlorine by physical processes. Hence, it is a compound.

Key Concept: Pure Substances and Compounds

d) Sugar
[Solution Description]
A pure substance consists of only one type of particle and cannot be separated into other substances by physical means. Among the options, sugar is a compound made of carbon, hydrogen, and oxygen in fixed proportions, which cannot be separated physically. Milk is a mixture, bottled juice contains multiple components, and soil is heterogeneous.

Key Concept: Separation of Compounds

c) Because physical methods cannot break chemical bonds
[Solution Description]
Water is a compound where hydrogen and oxygen are chemically bonded in a fixed ratio (2:1). The chemical bonds between them are strong and require energy to break, making physical separation impossible. Only chemical processes like electrolysis can separate them.

Key Concept: Pure Substances – Water as a Compound

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
Water is a pure substance because it is made up of only one type of particle (H$_2$O molecules). The reason states that water consists of hydrogen and oxygen chemically combined in a fixed ratio (2:1), which is correct and explains why water is a pure substance (a compound). Thus, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Pure Substances, Compounds

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that water is a pure substance because it cannot be separated into hydrogen and oxygen by physical methods. This is true as water ($H_2O$) is a compound where hydrogen and oxygen are chemically bonded in a fixed ratio (2:1) and require chemical methods like electrolysis for separation.
The reason states that pure substances consist of the same type of particles and cannot be separated by physical processes. This is also true and directly explains why water qualifies as a pure substance—it meets both criteria mentioned in the reason.
Thus, both Assertion and Reason are true, and Reason correctly explains Assertion.

Key Concept: Compounds, Element combinations

c) Sugar is a compound composed of carbon, hydrogen, and oxygen.
[Solution Description]
Sugar decomposing into carbon and water vapor indicates that it is not an element but a compound made up of carbon, hydrogen, and oxygen. Elements do not decompose into simpler substances under normal conditions, whereas compounds can break down into their constituent elements or simpler compounds.

Key Concept: Pure substances, Compounds

b) It consists of uniform composition with identical particles.
[Solution Description]
A pure substance consists of only one type of particle and cannot be separated into other kinds of matter by any physical process. Mixtures contain multiple types of particles that can be separated physically. The key distinction is the uniformity and indivisibility of particles in a pure substance.

Key Concept: Compounds as Pure Substances

b) Because it is composed of hydrogen and oxygen chemically combined in a fixed ratio
[Solution Description]
Water is a compound because it consists of hydrogen and oxygen chemically combined in a fixed ratio (2:1). Its properties differ from those of its constituent elements, and it cannot be separated into hydrogen and oxygen by physical methods.

Key Concept: Definition of Pure Substance

b) A substance with no other substances mixed in it and made of identical particles
[Solution Description]
A pure substance, according to science, consists of the same type of particles and cannot be separated into other substances by physical processes. It is not merely unadulterated but must have uniform composition.

Key Concept: Pure Substances and Compounds

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that common salt (sodium chloride) is a pure substance, which is true because it consists of the same type of particles (NaCl molecules) in a fixed ratio (1:1). The reason claims that sodium chloride can be separated into sodium and chlorine by physical processes, which is false. Sodium chloride can only be separated into its constituent elements (sodium and chlorine) through chemical processes like electrolysis, not physical processes such as evaporation or filtration. Therefore, Assertion is true, but Reason is false.

Key Concept: Examples of Pure Substances

c) Common salt (sodium chloride)
[Solution Description]
Common salt (sodium chloride) is a compound formed by chemically combining sodium and chlorine in a fixed ratio. It cannot be separated into its constituents by physical means, making it a pure substance.

Key Concept: Native minerals vs. compound minerals, applications

b) Copper
[Solution Description]
Native minerals are pure elements. Copper is a native metal widely used in electrical wiring due to its excellent conductivity.

Key Concept: Minerals and Their Uses

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that talcum powder is made from the mineral talc due to its softness and lubricating properties, which is correct as talc is indeed used for these characteristics. However, the reason claims that talc is a pure element, which is false. Talc is not a pure element but a compound with the chemical formula $Mg_3Si_4O_{10}(OH)_2$, composed of magnesium, silicon, oxygen, and hydrogen. Hence, the Assertion is true, but the Reason is false.

Key Concept: Mineral composition, cement production

c) Talc
[Solution Description]
Cement is primarily made from calcite, quartz, alumina, and iron oxide. Talc is not used in cement production; it is the main mineral in talcum powder.

Key Concept: Minerals in everyday products

c) Talcum powder
[Solution Description]
Talcum powder is directly derived from the mineral talc, which is known for its softness and moisture-absorbing properties.

Key Concept: Minerals and Their Uses

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that cement is made from specific minerals like calcite, quartz, alumina, and iron oxide, which is correct as per the syllabus. The reason states that talcum powder is derived from the mineral talc, which is also accurate according to the syllabus. However, the reason does not explain why the assertion is true; they are two independent facts about different minerals and their uses.