Key Concept: Temperature Measurement and Perception

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that our sense of touch is unreliable for measuring temperature, which aligns with the syllabus's emphasis on the limitations of touch-based temperature assessment. The reason describes Activity 7.1, where varying sensations arise from prior exposure to different temperatures, supporting the assertion. Both the assertion and reason are true, and the reason correctly explains why touch is unreliable.

Key Concept: General Introduction

a) Missing syllabus
[Solution Description]

Key Concept: General Introduction

a) Content needed
[Solution Description]

Key Concept: Temperature Measurement

b) Thermometer gives an exact numerical value
[Solution Description]
Touching someone's forehead can give a rough idea of their temperature, but it is not accurate. A thermometer provides a precise numerical measurement, ensuring reliability. The story emphasizes that Phiban used a thermometer to confirm Lambok's normal temperature after initially suspecting fever through touch.

Key Concept: Digital thermometers vs Mercury thermometers

d) Mercury is toxic and difficult to dispose of safely, making digital thermometers safer.
[Solution Description]
Mercury thermometers contain mercury, a toxic substance that poses health risks if the thermometer breaks. Digital thermometers do not contain hazardous materials and are easier to read due to their digital displays. They also reduce environmental hazards associated with mercury disposal.

Key Concept: Precautions in Using a Thermometer

b) Wash the thermometer tip with soap and water
[Solution Description]
According to the story, Phiban washed the thermometer tip with soap and water before use. This ensures hygiene and prevents contamination when measuring someone's temperature. Proper cleaning is essential both before and after use.

Key Concept: Temperature Measurement

c) Temperature
[Solution Description]
The reliable measure of hotness or coldness of a body is its temperature, as defined in the syllabus.

Key Concept: Temperature Conversion

d) 303.15 K
[Solution Description]
Using the formula from the syllabus: $Temperature\ in\ Kelvin = Temperature\ in\ Celsius + 273.15$. So, $30 + 273.15 = 303.15 K$.

Key Concept: Temperature measurement, Clinical thermometer

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the precautions for using a digital clinical thermometer, one must avoid holding it by the tip as it can lead to inaccurate readings due to heat transfer from the hand. The assertion correctly states this precaution. The reason provided explains why holding the tip affects accuracy, which directly supports the assertion.
Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Temperature Measurement

c) Human touch varies and is not precise
[Solution Description]
Human touch is subjective and varies from person to person. It cannot provide a precise or consistent measurement of temperature, as it depends on individual perception and external conditions like ambient temperature. A thermometer provides an objective and reliable measure.

Key Concept: Clinical and Laboratory Thermometers, Temperature Measurement

c) The thermometer is not designed for measuring high temperatures outside its range.
[Solution Description]
Clinical thermometers are designed to measure human body temperature, typically within the range of 95$^\circ$F to 110$^\circ$F. Using it to measure higher temperatures (like boiling liquids) can damage the thermometer or give inaccurate readings since it is not calibrated for such extremes. Laboratory thermometers are designed for broader ranges and precise measurements beyond human body temperatures.

Key Concept: Importance of Reliable Instruments

b) They eliminate subjectivity and provide accurate measurements
[Solution Description]
Thermometers provide an accurate, standardized measurement of temperature, eliminating the subjectivity and inconsistency associated with human touch. They ensure reliable and repeatable results, crucial for scientific and medical purposes.

Key Concept: Thermometer Types

c) Clinical thermometer
[Solution Description]
Clinical thermometers are used to measure human body temperatures accurately. They can be digital or mercury-based, but both types are calibrated for body temperature ranges.

Key Concept: Relative hotness, Temperature difference

c) Body Y is hotter than body X by $30^\circ C$.
[Solution Description]
Temperature is a reliable measure of hotness. A body with a higher temperature is hotter than a body with a lower temperature. Here, Y has a higher temperature ($70^\circ C$) than X ($40^\circ C$), so Y is hotter than X by $30^\circ C$.

Key Concept: Reliable measure of hotness or coldness

c) Temperature
[Solution Description]
According to the syllabus, a reliable measure of hotness or coldness of a body is its temperature. The temperature of a hotter body will be higher than that of a colder body.

Key Concept: Thermal perception, Temperature measurement

b) The ice water hand feels warmth while the warm water hand feels coolness
[Solution Description]
The hand from ice water will feel the room temperature water as warm because its baseline temperature was much lower (5°C to 25°C is a warming sensation). The hand from warm water will feel the same room temperature water as cool because its baseline was higher (45°C to 25°C is a cooling sensation). This demonstrates that human touch perception of temperature is relative rather than absolute, making it unreliable for precise temperature measurement.

Key Concept: Reliability of Sense of Touch

c) The right hand will feel the tap water as cool and the left hand as warm
[Solution Description]
When the right hand is dipped in warm water, it gets accustomed to the higher temperature. After transferring it to tap water, which is cooler than warm water, the right hand perceives the tap water as cool. Conversely, the left hand, initially dipped in ice-cold water, gets used to the lower temperature. When placed in tap water, which is warmer than ice-cold water, the left hand perceives the tap water as warm. This happens because our sense of touch is relative to the previous temperature experienced.

Key Concept: Practical Implications

d) Using a thermometer
[Solution Description]
Using an external measuring device like a thermometer provides an objective and consistent measurement of temperature, unlike our sense of touch which is subjective and variable. A thermometer measures the actual temperature without being influenced by prior conditions or personal perception.

Key Concept: Temperature measurement devices

c) Digital thermometers are safer and easier to read
[Solution Description]
Mercury thermometers contain mercury, which is a toxic substance and poses health risks if the thermometer breaks. Digital thermometers, on the other hand, use heat sensors to measure temperature and display the reading digitally, making them safer and easier to read. They also eliminate the risk of mercury poisoning, which is why they are preferred over mercury thermometers for measuring body temperature.

Key Concept: Limitations of sense of touch

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that our sense of touch cannot always accurately determine whether a body is hot or cold, which is true as demonstrated in Activity 7.1 where the same water felt warm to one hand and cool to the other due to prior exposure to different temperatures. The reason explains that the sense of touch is influenced by temperature adaptation, which is also true. However, the reason does not completely explain why the sense of touch fails to provide accurate measurements under all conditions—it only points to one factor affecting it. Therefore, both statements are true, but the reason is not the correct explanation of the assertion.

Key Concept: Limitations of sense of touch

b) Our sense of touch depends on the previous state of our hands
[Solution Description]
The sense of touch is relative and depends on the previous state of our hands. If one hand was in warm water and the other in cold water, dipping both into tap water will make the first feel cool and the second feel warm. This shows that our sense of touch is not absolute but influenced by prior exposure.

Key Concept: Comparing water in three containers

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that after dipping one hand in warm water and another in ice-cold water, placing both hands in tap water will make the first hand feel it as cool and the second as warm. The reason explains that this occurs because our sense of touch is unreliable for measuring temperature, and perception depends on the initial temperature of the hands. Both statements are true, and the reason correctly explains the assertion.

Key Concept: Reliability of touch

c) Because prior exposure alters temperature perception
[Solution Description]
The sense of touch is unreliable for temperature because prior exposure changes our perception. The right hand was in warm water, making tap water feel cooler. The left hand was in cold water, making tap water feel warmer. This shows sensory adaptation affects temperature judgment.

Key Concept: Temperature perception, relative hotness/coldness

c) Right hand feels cool, left hand feels warm
[Solution Description]
After keeping the right hand in warm water, the hand adjusts to the higher temperature. When moved to tap water (B), which is cooler than A but warmer than C, the right hand perceives it as cool. Conversely, the left hand adjusts to the cold temperature of C, so tap water (B) feels warm compared to C.

Key Concept: Temperature Perception

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion describes what happens when hands are dipped in warm and cold water and then placed in tap water. This is true because skin senses temperature relative to its current state. After exposure to warm water, the right hand adapts and perceives tap water as cooler compared to its previous state. Similarly, after exposure to ice-cold water, the left hand perceives tap water as warmer. The Reason explains why this happens: our sense of touch does not measure absolute temperature but compares it with the baseline set by prior exposure. Hence, both Assertion and Reason are correct, and the Reason provides the correct explanation.

Key Concept: Inference: Why touch is unreliable for temperature comparison

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that our sense of touch gives varying perceptions of the same water temperature based on prior exposure, which aligns with the observation in Activity 7.1 where hands exposed to warm and cold water perceived tap water differently. The reason explains this phenomenon by stating that the prior temperature state of our hands influences perception, which is directly supported by the inference from the activity. Thus, both are true, and the reason correctly explains the assertion.

Key Concept: Thermometer Purpose

b) To provide a reliable measure of hotness or coldness
[Solution Description]
A thermometer provides a reliable measure of temperature because it measures hotness or coldness objectively without being influenced by external factors like human perception. The conclusion from Activity 7.1 emphasized that a thermometer is necessary for accurate temperature measurement.

Key Concept: Temperature Measurement, Clinical and Laboratory Thermometers

d) Assertion is false, but Reason is true.
[Solution Description]
- Assertion (A) states that a laboratory thermometer with a range up to $110 \degree C$ cannot measure the temperature of boiling water accurately.
- Reason (R) states that the boiling point of water at standard atmospheric pressure is $100 \degree C$.
- The boiling point of water is indeed $100 \degree C$ under standard conditions, which is within the range of the thermometer ($-10 \degree C$ to $110 \degree C$). Therefore, the thermometer can measure the temperature of boiling water accurately.
- Thus, Assertion (A) is false because the thermometer's range includes $100 \degree C$, but Reason (R) is true as it correctly states the boiling point of water.

Key Concept: Temperature Measurement

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the normal temperature of a healthy human adult is $37.0 °C$, which is correct as per the syllabus. The reason states that a clinical thermometer is used to measure body temperature, which is also correct. Furthermore, the reason correctly explains why we know the normal body temperature is $37.0 °C$, because it is measured using a clinical thermometer. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Temperature Scales

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the Kelvin scale is more scientific than the Celsius scale, which is true because the Kelvin scale is an absolute temperature scale with its zero point at absolute zero ($0 K$ or $-273.15°C$), a fundamental limit in thermodynamics. The reason correctly explains that the Kelvin scale starts at absolute zero, where all molecular motion theoretically stops. This makes it scientifically preferable for thermodynamic calculations.

Key Concept: Temperature Scales

c) Kelvin scale
[Solution Description]
The Kelvin scale starts from absolute zero and is commonly used in scientific measurements, unlike Celsius and Fahrenheit scales which have arbitrary reference points.

Key Concept: Temperature Scales Comparison

a) 10 K
[Solution Description]
Since the Kelvin scale and Celsius scale have the same size of unit increments (1 K = 1 $°$C), a change of 10 $°$C corresponds to a change of 10 K. The offset of 273.15 does not affect the difference.

Key Concept: Conceptual understanding of absolute zero

c) $-273.15^{\circ}C$
[Solution Description]
Absolute zero is the lowest limit of temperature where all thermal motion ceases. On the Celsius scale, absolute zero is $-273.15^{\circ}C$, which corresponds to $0K$.

Key Concept: Thermometer Usage

b) Laboratory thermometer
[Solution Description]
A clinical thermometer is not suitable for measuring the temperature of boiling water as it has a limited range (around $35 \degree C$ to $42 \degree C$). A laboratory thermometer is designed for a wider range, typically $-10 \degree C$ to $110 \degree C$, making it suitable for measuring boiling water.
Therefore, the correct thermometer to use is the laboratory thermometer.

Key Concept: Temperature Scales

c) Kelvin
[Solution Description]
The SI unit of temperature is kelvin, denoted by $K$. This is directly mentioned in the syllabus under "Temperature Scales."

Key Concept: Temperature Measurement

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
Assertion states that a clinical thermometer cannot measure the temperature of boiling water, which is true because the range of a clinical thermometer is typically between $35\,^{\circ}C$ and $42\,^{\circ}C$. Boiling water has a temperature of $100\,^{\circ}C$, which is outside this range. Reason explains that the range of a clinical thermometer is limited to normal human body temperatures, which is also correct. Moreover, the reason correctly justifies why the assertion is true. Hence, both are true, and the reason correctly explains the assertion.

Key Concept: Thermometer Liquids

c) Colored alcohol
[Solution Description]
Traditional mercury thermometers are being phased out because mercury is toxic and difficult to dispose of safely. Modern laboratory thermometers often use colored alcohol (typically dyed red for visibility) as it is safer than mercury and provides accurate readings.

Key Concept: Clinical and Laboratory Thermometers, Temperature Conversion

b) 310.15 K
[Solution Description]
To convert Fahrenheit to Kelvin, follow these steps:
1. Convert Fahrenheit to Celsius using the formula: $C = \frac{5}{9}(F - 32)$.
2. Substitute $F = 98.6$ into the formula: $C = \frac{5}{9}(98.6 - 32) = \frac{5}{9} \times 66.6 = 37^\circ C$.
3. Convert Celsius to Kelvin using the formula: $K = C + 273.15$.
4. Substitute $C = 37$ into the formula: $K = 37 + 273.15 = 310.15 K$.
The equivalent reading is 310.15 K.

Key Concept: Laboratory Thermometer Precaution

c) Do not hold it by the bulb
[Solution Description]
Laboratory thermometers are fragile and must be handled carefully to avoid breakage. Additionally, holding the thermometer by the bulb can affect the temperature reading due to heat transfer from the hand. Therefore, it should not be held by the bulb.

Key Concept: Clinical Thermometer

c) Measuring body temperature
[Solution Description]
A clinical thermometer is specifically designed to measure human body temperature, as mentioned in the syllabus. It is commonly used in medical settings.

Key Concept: Laboratory Thermometer

c) Alcohol or mercury
[Solution Description]
Laboratory thermometers commonly use either alcohol (colored red) or mercury as the liquid, as stated in the syllabus. However, due to toxicity issues, mercury is being phased out.

Key Concept: Infrared Thermometer, Non-Contact Measurement

b) They can measure temperature from a distance without contact.
[Solution Description]
Infrared thermometers measure temperature without physical contact, reducing the risk of disease transmission. This makes them ideal for crowded places where hygiene and quick screening are critical.

Key Concept: Clinical Thermometer, Laboratory Thermometer

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that a laboratory thermometer must be read while immersed in the liquid. This is correct because, as per the syllabus, the temperature must be read while the thermometer is immersed in water to avoid any changes due to external temperature variations. The reason explains that removing the thermometer can cause rapid cooling or heating of the bulb, leading to inaccurate readings. This correctly justifies the assertion.

Key Concept: Clinical Thermometer

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that the normal human body temperature is $37.0\,^\circ\text{C}$, which is true according to the syllabus. However, the reason claims that a clinical thermometer measures temperatures from $-10\,^\circ\text{C}$ to $110\,^\circ\text{C}$, which is false as this range is for a laboratory thermometer. A clinical thermometer typically measures temperatures close to the human body temperature range ($35\,^\circ\text{C}$ to $42\,^\circ\text{C}$). Thus, the assertion is true, but the reason is false.

Key Concept: Temperature Conversion

a) $98.6\,^{\circ}\text{F}$
[Solution Description]
Using the conversion formula $F = \frac{9}{5}C + 32$, we substitute $C = 37$. First, multiply 37 by $\frac{9}{5}$ which gives $\frac{333}{5} = 66.6$. Then add 32 to get $66.6 + 32 = 98.6\,^{\circ}\text{F}$.

Key Concept: Clinical Thermometer Features

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that digital clinical thermometers use heat sensors for accurate measurement, which is true as per the syllabus. The reason explains how these sensors work by converting temperature into electrical signals, leading to numerical display, which is also correct and directly explains the assertion.

Key Concept: Infrared Thermometers

a) They can measure body temperature from a distance.
[Solution Description]
Infrared thermometers measure temperature without physical contact, reducing the risk of disease transmission. This feature made them particularly useful during the COVID-19 pandemic for safe temperature screening.

Key Concept: Types of Thermometers

d) Infrared thermometers.
[Solution Description]
Non-contact (infrared) thermometers were used during the COVID-19 pandemic to measure body temperature from a distance, reducing disease transmission risk.

Key Concept: Precautions While Using Digital Clinical Thermometers

b) Hold the thermometer by the tip while measuring
[Solution Description]
According to standard precautions, the thermometer tip should be cleaned before and after use, and it should not be held by the tip to avoid contamination or damage. However, placing the thermometer under the armpit is not recommended for accurate oral readings, as it may give less precise results compared to placing it under the tongue.

Key Concept: Use of Clinical Thermometers

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that digital clinical thermometers are preferred over mercury thermometers for measuring body temperature. This is true because digital thermometers offer advantages such as non-toxicity (no mercury) and ease of reading from a digital display. The Reason given is that digital thermometers pose no toxic risk and have easier-to-read displays, which directly explains why they are preferred over mercury thermometers. Both the Assertion and Reason are factually correct, and the Reason logically justifies the Assertion.

Key Concept: Transition from Mercury to Digital Thermometers

c) Mercury is toxic and difficult to dispose of safely
[Solution Description]
Mercury thermometers contain toxic mercury, which is hazardous if the thermometer breaks. Digital thermometers are safer, easier to read (digital display), and more environmentally friendly. They do not pose the same risks as mercury thermometers.

Key Concept: Digital Thermometer Features

a) Measures temperature from a distance
[Solution Description]
Digital clinical thermometers use heat sensors, display temperature digitally, and are safer than mercury thermometers. They do not measure temperature from a distance, which is a feature of infrared thermometers.

Key Concept: Infrared Thermometer Use

c) They reduce the risk of disease transmission
[Solution Description]
Infrared thermometers are non-contact, reducing the risk of disease transmission. This was crucial during the COVID-19 pandemic to minimize physical contact and prevent the spread of the virus.

Key Concept: Infrared Thermometer, Disease Spread Prevention

c) Non-contact operation reduces disease transmission risk
[Solution Description]
Infrared thermometers allow non-contact temperature measurement, reducing physical contact and thus minimizing the risk of disease transmission—a crucial advantage during pandemics like COVID-19 where close contact poses infection risks.

Key Concept: Precautions for Digital Thermometers

b) Wash the tip with soap and water before and after use.
[Solution Description]
Proper precautions include washing the tip before and after use, keeping the display dry, and not holding the thermometer by its tip.

Key Concept: Clinical Thermometer Range

c) $37.0\,^\circ C$
[Solution Description]
The normal temperature of a healthy human adult is given in the syllabus as $37.0\,^\circ C$ or $98.6\,^\circ F$. Since clinical thermometers commonly use the Celsius scale, the correct answer is $37.0\,^\circ C$.

Key Concept: Clinical thermometers

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that digital clinical thermometers are safer to use than mercury thermometers, which is true because digital thermometers do not contain hazardous materials like mercury. The reason given is that mercury is a toxic substance and poses disposal hazards if the thermometer breaks, which is also true. Moreover, the reason correctly explains why digital thermometers are safer, as they eliminate the risks associated with mercury.

Key Concept: Temperature Conversion

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, the formula for converting Celsius to Kelvin is:
$Temperature \ in \ Kelvin = Temperature \ in \ Celsius + 273.15$.
Step 1: Start with the given Celsius temperature, which is 25 \textdegree C.
Step 2: Add 273.15 to the Celsius temperature as per the formula.
Calculation:
$25 + 273.15 = 298.15$
Thus, 25 \textdegree C equals 298.15 K.
The Assertion and Reason are both true, and the Reason correctly explains the conversion process.

Key Concept: Temperature Scale Units

c) K
[Solution Description]
The Kelvin scale's unit is "kelvin" and its symbol is "K". Unlike Celsius (°C) and Fahrenheit (°F), it does not use the degree symbol (°). Therefore, the correct representation is simply "K".

Key Concept: Fahrenheit to Celsius conversion, Clinical thermometer range

c) This temperature is outside the measurable range of a clinical thermometer.
[Solution Description]
First, convert 212 °F to Celsius using $°C = \frac{5}{9}(°F - 32)$. Substituting, $°C = \frac{5}{9}(212 - 32) = \frac{5}{9} \times 180 = 100$ °C. The clinical thermometer range is 35 °C to 42 °C. Since 100 °C is outside this range, the clinical thermometer cannot measure it accurately.

Key Concept: Digital vs Mercury Thermometers

c) Digital thermometers are non-toxic and easier to read compared to mercury thermometers
[Solution Description]
Mercury thermometers contain toxic mercury, which poses health and environmental risks if the thermometer breaks. Digital thermometers eliminate this risk and provide easier-to-read displays. Additionally, digital thermometers use heat sensors, making them safer and more convenient, especially in clinical settings.

Key Concept: Precautions while using a clinical thermometer, Digital vs Mercury thermometers

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states the precaution of washing the tip of a digital clinical thermometer before and after use. This is correct as it helps maintain hygiene and prevents contamination. The reason explains that washing removes bacteria (preventing cross-contamination) and keeping the digital portion dry ensures the device functions properly. Both statements are true, and the reason correctly explains the assertion.

Key Concept: Mercury Thermometer Risks, Disposal

c) Mercury is toxic and difficult to dispose of safely.
[Solution Description]
Mercury is highly toxic and poses health risks if the thermometer breaks. Disposing of broken mercury thermometers is also hazardous. Digital thermometers, being safer and easier to read, have replaced them.

Key Concept: Factors affecting body temperature

d) All of the above
[Solution Description]
The syllabus mentions that body temperature is influenced by age, time of the day, and activity level. These are the key factors affecting body temperature variations.

Key Concept: Time-of-day variation, percentage change

b) 2.16\%
[Solution Description]
Calculate difference from normal temp (37.0°C):
Morning diff = $37.0 - 36.6 = 0.4\,°C$ below normal
Evening diff = $37.4 - 37.0 = 0.4\,°C$ above normal
Total change = $0.4 + 0.4 = 0.8\,°C$
Percentage increase relative to normal temp: $(0.8/37.0) \times 100 \approx 2.16\%$

Key Concept: Temperature scales comparison, Kelvin conversion

c) 309.35\,K
[Solution Description]
Actual core temperature = Axillary reading + 0.4°C = $35.8 + 0.4 = 36.2\,°C$
Convert to Kelvin: $K = °C + 273.15 = 36.2 + 273.15 = 309.35\,K$
Rounding to two decimal places: $309.35\,K$

Key Concept: Smallest Measurable Value Calculation

b) $1 \, ^\circ C$
[Solution Description]
To find the smallest measurable value, calculate the temperature difference between two consecutive big marks: $30 \, ^\circ C - 20 \, ^\circ C = 10 \, ^\circ C$. Now divide this by the number of small divisions: $10 \, ^\circ C / 10 = 1 \, ^\circ C$. So, each small division represents $1 \, ^\circ C$.

Key Concept: Smallest Division, Range, Application

c) 98.5\ \degree C
[Solution Description]
Given:
- Major markings: $98\ \degree C$ and $99\ \degree C$.
- Smallest division = $1\ \degree C$.
Halfway between $98\ \degree C$ and $99\ \degree C$ corresponds to:
$98\ \degree C + \left(\frac{1\ \degree C}{2}\right) = 98.5\ \degree C$
Since the thermometer's smallest division is $1\ \degree C$, it can measure only whole numbers. Hence, the student must approximate the reading.

Key Concept: Laboratory Thermometer - Precautions

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the bulb of the thermometer should not touch the sides or bottom of the container when measuring temperature. This is a standard precaution mentioned in the syllabus to ensure accurate readings. The reason explains that this prevents uneven heating and incorrect readings, which is correct and directly explains why the assertion is true.

Key Concept: Correct Way to Measure Temperature

d) Hold the thermometer vertically without the bulb touching the beaker's side or bottom
[Solution Description]
The syllabus states that the thermometer should be held vertically, the bulb should not touch the sides or bottom of the beaker, and the temperature must be read while the thermometer is still immersed in water.

Key Concept: Structure and Working of Laboratory Thermometer, Precautions

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, a key precaution for using a laboratory thermometer is that the temperature must be read while the thermometer is still immersed in the liquid. This is because the liquid column rises or falls based on temperature changes. If the thermometer is taken out, the liquid column falls due to cooling, giving an incorrect lower temperature reading. Hence, both Assertion (A) and Reason (R) are true, and R correctly explains why the thermometer must be read while immersed.

Key Concept: Temperature Measurement Precautions

c) Keep it immersed and align the eye with the liquid column
[Solution Description]
The correct way to measure temperature with a laboratory thermometer is to keep it immersed in the liquid and align the eye level with the top of the liquid column to avoid parallax error. Readings must be taken while immersed because the liquid column falls when removed.

Key Concept: Range, smallest division

b) $\pm 0.29^{\circ}C$
[Solution Description]
First, find the smallest division: The difference between $30^{\circ}C$ and $40^{\circ}C$ is $10^{\circ}C$ spread over 17 divisions. Each small division = $10/17 = 0.588^{\circ}C$. Uncertainty when reading is midway between two divisions is half of the smallest division = $0.588/2 = 0.294^{\circ}C$.

Key Concept: Range, smallest division, unit conversion

b) $0.63^{\circ}C$
[Solution Description]
Step 1: Calculate smallest division in $^{\circ}F$. Difference between $50^{\circ}F$ and $100^{\circ}F$ = $50^{\circ}F$ with 44 divisions. Each division = $50/44 = 1.136^{\circ}F$.
Step 2: Convert to $^{\circ}C$ using the midpoint of one division: For $1.136^{\circ}F$ change, $\Delta C = 1.136 \times \frac{5}{9} = 0.631^{\circ}C$.

Key Concept: Smallest Division

b) 0.5 °C
[Solution Description]
The smallest division is calculated by dividing the difference between two big marks by the number of divisions. Here, the difference is $40\ °C - 30\ °C = 10\ °C$, and there are 20 divisions. So, the smallest division is $10\ °C / 20 = 0.5\ °C$.

Key Concept: Measuring temperature of warm water

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the liquid column stops rising due to thermal equilibrium. This is correct because, according to thermodynamic principles, heat transfer continues until both bodies (thermometer and water) reach the same temperature, at which point thermal equilibrium is achieved. The reason correctly explains this phenomenon by stating that no further net heat transfer occurs once both are at the same temperature. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Measuring temperature, Liquid column behavior

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that the liquid column falls when the thermometer is taken out of warm water due to the cooler surrounding air. This is true because the liquid inside the thermometer contracts as it cools down upon exposure to the lower ambient temperature. The reason claims that the temperature must be read while the thermometer is immersed for accuracy, which is also correct since taking it out leads to an immediate change in temperature measurement. However, the falling of the liquid column is a result of the temperature difference, but the reason provided does not directly explain why the column falls—it only emphasizes the need for immersion during reading. Therefore, both statements are true, but the reason does not correctly explain the assertion.

Key Concept: Correct way of measuring temperature

c) Vertically
[Solution Description]
According to the syllabus, the thermometer must be held vertically (straight up and down) for accurate reading. Tilting it may give incorrect measurements.

Key Concept: Precautions, Correct usage

b) The heat from the hand alters the bulb temperature
[Solution Description]
Holding the thermometer by the bulb can transfer heat from the hand to the bulb, affecting the accuracy of the measurement. The syllabus specifies that the thermometer should not be held by the bulb as part of standard precautions.

Key Concept: Correct usage of laboratory thermometer

a) It gives inaccurate readings for body temperature
[Solution Description]
Laboratory thermometers are designed for measuring temperatures in experiments, not for body temperature. They may not provide accurate readings for body temperature due to different design specifications. Also, mercury thermometers pose health risks if broken.

Key Concept: Precautions for using a laboratory thermometer

c) Read the temperature while immersed, keeping the eye directly in line with the liquid column
[Solution Description]
The thermometer should be immersed in water such that its bulb does not touch the bottom or sides of the beaker. It must be held vertically and not tilted. The temperature must be read while the thermometer is still immersed in water, with the eye directly in line with the liquid column level.

Key Concept: Human body temperature, Measurement accuracy

c) Range of $35^{\circ}C$ to $42^{\circ}C$ with $0.1^{\circ}C$ divisions
[Solution Description]
To measure $39.5^{\circ}C$ accurately with $\pm0.1^{\circ}C$ precision, the thermometer must include $39.5^{\circ}C$ within its range and have divisions of at least $0.1^{\circ}C$. Clinical thermometers (35-42$^{\circ}C$, $0.1^{\circ}C$ divisions) meet these requirements, unlike others with wider ranges or coarser graduations.

Key Concept: Thermometer Range

b) -10$^{\circ}\text{C}$ to 110$^{\circ}\text{C}$
[Solution Description]
The problem requires identifying a thermometer that can measure $-5^{\circ}\text{C}$. Based on the syllabus, the range of a laboratory thermometer is provided as an example, but weather thermometers must cover lower temperatures. The correct thermometer should include negative values. Option (ii) specifies $-10^{\circ}\text{C}$ to $110^{\circ}\text{C}$, which covers $-5^{\circ}\text{C}$.

Key Concept: Temperature Conversion

c) 86$^{\circ}\text{F}$
[Solution Description]
To convert Celsius to Fahrenheit, use the formula: $F = \frac{9}{5} \times C + 32$. Plugging in 30$^{\circ}\text{C}$:
$F = \frac{9}{5} \times 30 + 32 = 54 + 32 = 86^{\circ}\text{F}$
Thus, the conversion yields 86$^{\circ}\text{F}$.

Key Concept: Air Temperature

b) Laboratory thermometer
[Solution Description]
Weather stations use thermometers designed to monitor air temperature. These are often placed in shaded areas to avoid direct sunlight affecting the readings.

Key Concept: Laboratory Thermometer

b) $-10^{\circ}C$ to $110^{\circ}C$
[Solution Description]
Laboratory thermometers are designed for a wide range of temperatures to be useful in various experiments. The syllabus specifies that their typical range is from $-10^{\circ}C$ to $110^{\circ}C$. This range allows them to measure below freezing and above boiling points of water, making them versatile for lab use.

Key Concept: Clinical thermometer, Digital thermometer

b) 38.3$^\circ$C to 38.7$^\circ$C
[Solution Description]
The digital thermometer reads 38.5$^\circ$C accurately. The mercury thermometer has an error margin of $\pm0.2^\circ$C. So, the actual temperature could be between $38.5^\circ C - 0.2^\circ C = 38.3^\circ C$ and $38.5^\circ C + 0.2^\circ C = 38.7^\circ C$.

Key Concept: Air Temperature Measurement

c) Maximum-minimum thermometer
[Solution Description]
Weather stations use specialized thermometers to record daily maximum and minimum air temperatures. These measurements are crucial for weather forecasting and are typically done using instruments like maximum-minimum thermometers or digital data loggers designed for environmental monitoring.

Key Concept: Measuring Air Temperature

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that weather reports include maximum and minimum air temperatures because they provide important information about daily weather conditions. This is true as these values help understand the temperature fluctuations throughout the day. The reason given is that maximum and minimum air temperatures help in predicting weather patterns and are key parameters for meteorological analysis. This is also true, as these values are crucial for weather forecasting. Moreover, the reason correctly explains why these temperatures are included in weather reports, as they directly contribute to understanding and predicting weather conditions.

Key Concept: Maximum-minimum temperature variation, Data analysis

c) 10$^\circ$C
[Solution Description]
The daily range is calculated as maximum temperature minus minimum temperature.
For all days: Range = Max - Min = $35-25=10^\circ C$, $36-26=10^\circ C$, etc.
Thus, the consistent daily range is $10^\circ C$.

Key Concept: Recording maximum and minimum temperature

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that the highest temperature recorded in a day is called the maximum temperature, which is true as per the syllabus. However, the reason claims that maximum temperature is always recorded during noon when the Sun is directly overhead, which is not necessarily true. While the Sun's position affects temperature, other factors like cloud cover, humidity, and wind can shift the time of peak temperature. Therefore, the assertion is true, but the reason is false.

Key Concept: Temperature Measurement

b) 1 °C
[Solution Description]
The thermometer has a range from $0 °C$ to $100 °C$. Between two bigger marks, there are 10 divisions. The temperature difference between two bigger marks is $10 °C$. To find the smallest measurable temperature, divide the difference by the number of divisions: $\frac{10 °C}{10} = 1 °C$.

Key Concept: Air Temperature and Weather Forecasting

c) Making weather forecasts
[Solution Description]
Air temperature data is crucial for weather forecasting as it helps predict weather patterns, seasonal changes, and extreme conditions. The syllabus states that "Air temperature is an important weather parameter...used for making weather forecasts."

Key Concept: Kelvin scale, Temperature conversion

b) 76.85$^\circ$C, 170.33$^\circ$F
[Solution Description]
Convert Kelvin to Celsius using the formula $^\circ C = K - 273.15$.
$^\circ C = 350 - 273.15 = 76.85^\circ C$.
Now convert Celsius to Fahrenheit using $^\circ F = \left(\frac{9}{5} \times ^\circ C\right) + 32$.
$^\circ F = \left(\frac{9}{5} \times 76.85\right) + 32 \approx 170.33^\circ F$.

Key Concept: Air Temperature and Weather Forecasting

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, air temperature is a critical parameter for weather forecasting. Weather stations globally monitor it alongside other parameters to predict weather patterns. The Assertion states that monitoring air temperature is essential for accurate weather forecasting, which is true as per the syllabus. The Reason explains that air temperature data helps in predicting seasonal variations and daily weather patterns, which is also true and directly supports the Assertion. Therefore, both are true, and the Reason correctly explains the Assertion.

Key Concept: Temperature Scales and Weather Forecasting

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that the Celsius scale is more commonly used in weather reports than the Kelvin scale. This is true because weather reports are meant for the general public, and $^\circ C$ is more relatable as water freezes at $0^\circ C$ and boils at $100^\circ C$.
The Reason explains that the Celsius scale is preferred due to its direct relation to human experiences, which is correct. Thus, both the Assertion and Reason are true, and the Reason correctly explains the Assertion.

Key Concept: Anna Mani's Contributions

b) The Weather Woman of India
[Solution Description]
Anna Mani was a renowned Indian scientist who made significant contributions to weather instrumentation, earning her the nickname 'Weather Woman of India'. Her work focused on developing indigenous instruments and advancing renewable energy.

Key Concept: Anna Mani's Contribution

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The syllabus states that Anna Mani invented and built a large number of weather measurement instruments, reducing India’s reliance on other nations for such instruments. This directly supports Assertion (A). Reason (R) also aligns with this information as eliminating imports would be a natural outcome of achieving self-reliance. Therefore, both Assertion and Reason are true, and Reason correctly explains Assertion.

Key Concept: Anna Mani's contributions, indigenous weather instruments

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
Anna Mani developed various indigenous weather instruments, reducing India's dependency on foreign imports. This was crucial for establishing reliable temperature measurement practices in both meteorological and medical fields. The Reason correctly explains the importance of accurate temperature measurement, which aligns with Anna Mani’s goal of achieving precision in weather instrumentation. Thus, both statements are true, and the Reason provides a valid explanation for the Assertion.

Key Concept: Renewable energy, Weather instrumentation

b) Accurate weather measurements are crucial for predicting wind and solar energy potential.
[Solution Description]
Anna Mani\'s development of accurate weather instruments provided essential data for harnessing wind and solar energy, making her work in both fields interdependent. The correct answer should explain how advancements in weather measurement directly supported renewable energy research.