Class 6 Science Chapter 1 The Wonderful World of Science

Key Concept: Scientific Method

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that science involves asking questions, making observations, and conducting experiments to understand the world, which aligns with the description of science in the syllabus. The reason explains that the scientific method provides a systematic way to answer questions through observation, hypothesis, experimentation, and analysis, which is also consistent with the syllabus. Moreover, the reason correctly explains why science follows this structured approach, as outlined in the syllabus. Hence, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Scientific Collaboration, Problem-Solving

b) Complex problems often require combined expertise and peer review
[Solution Description]
The scenario highlights teamwork in science, where diverse perspectives and skills accelerate problem-solving. Collaboration allows scientists to verify findings, identify errors, and integrate specialized knowledge—key aspects of the scientific method. As stated in the syllabus, “Scientists across the world work together, often in large teams.” This collective effort increases the reliability and creativity of solutions, unlike solo work, which may overlook critical angles or lack resources.

Key Concept: Science as Discovery, Curiosity

c) New findings can expand or revise existing knowledge
[Solution Description]
Science is dynamic, as new discoveries can build upon or even change previous understandings. Here, the initial discovery focused on attracting prey, but further research expanded the explanation to include confusing predators. This demonstrates how scientific knowledge evolves through continuous questioning, collaboration, and exploration. It aligns with the idea that science is “a giant and unending jigsaw puzzle,” where each new piece impacts the overall picture.

Key Concept: Scientific Method, Curiosity, Problem-Solving

b) Conduct an experiment with varying sunlight and measure plant growth
[Solution Description]
The scientific method involves testing hypotheses through controlled experiments. To validate if sunlight is essential for plant growth, the student must design an experiment where other variables (water, soil type) are kept constant, and only sunlight exposure is varied. Observations should be recorded over time to compare growth patterns.

Key Concept: Basic definition of Science

c) Curiosity and exploration
[Solution Description]
According to the syllabus, science is driven by curiosity and exploration. It involves observing, asking questions, and understanding how things work.

Key Concept: Curiosity, Exploration, Scientific Discovery

c) It fosters questioning and exploration leading to discoveries
[Solution Description]
Curiosity drives individuals to ask questions and seek answers, which is the basis of scientific inquiry. Without curiosity, there would be no motivation to explore or discover new phenomena. It leads to observations, hypotheses, and experiments, forming the foundation of science.

Key Concept: Scientific Method in Daily Life

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that fixing a bicycle tyre leak by checking different parts follows the scientific method. According to the syllabus, science involves asking questions and finding answers through observation, hypothesis, experimentation, and analysis. This matches the steps described in the reason. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Scientific Method

b) Guessing that adding more water will prevent sticking
[Solution Description]
Forming a hypothesis is the step where you propose a possible explanation for the observed phenomenon. Here, the observation is that rice sticks to the bottom of the pan. A hypothesis could be proposing that this happens due to insufficient water or high heat. The correct option should reflect making an educated guess about the cause.

Key Concept: Curiosity, Real-World Application

c) Compare historical weather data and habitat records to current observations.
[Solution Description] The observation (fewer butterflies) leads to questioning why. The scientist forms hypotheses (e.g., climate change reduced numbers) and designs experiments (e.g., comparing weather data or habitat maps across years) to test them, following the scientific method’s structured approach.

Key Concept: Scientific Thinking

c) Applying scientific method to solve problems
[Solution Description]
The mechanic’s approach shows practical application of the scientific method: observing a problem (flat tire), hypothesizing where the leak might be, testing through systematic examination (submerging in water), and analyzing results (bubbles show leak location). This demonstrates how scientific thinking applies to real-world problem solving.

Key Concept: Scientific Method

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that science follows a structured process to answer questions, which is true according to the syllabus. The reason describes the key steps of the scientific method—observing, questioning, guessing, testing, and analyzing—which is also accurate. Furthermore, the reason correctly explains why science involves a step-by-step process, as these steps form the foundation of scientific inquiry.

Key Concept: Nature of Science

c) New evidence can lead to the revision of existing theories.
[Solution Description]

Science is not a fixed body of knowledge—it is a dynamic and evolving process. As scientists make new observations, gather data, or develop improved technologies, they may find evidence that challenges or refines previous understandings. For example, older theories (like the geocentric model of the universe) have been replaced over time with better-supported ones (like the heliocentric model) as new evidence came to light.

This self-correcting nature of science—where theories and explanations can be modified, improved, or even replaced based on new evidence—is what makes science an ongoing and progressive process.

Key Concept: Science as Inquiry

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that science involves questioning and experimental testing to understand the world, which is true as per the syllabus. The reason explains that scientific knowledge is based on observation and hypothesis testing, which aligns with how science works as described in the syllabus. Moreover, the reason correctly explains why science follows this method—because it builds reliable knowledge through systematic inquiry. Thus, both are true, and the reason explains the assertion.

Key Concept: Science in Daily Life

b) Cooking food
[Solution Description]
Science is everywhere, including daily activities like cooking. Cooking involves chemical reactions and heat transfer, which are scientific concepts.

Key Concept: Celestial bodies, Scientific exploration

c) The galaxy is moving away from Earth.
[Solution Description]
The phenomenon of redshift occurs when light from an object increases in wavelength, shifting towards the red end of the spectrum. This is often due to the Doppler effect, which indicates the object is moving away from the observer. For galaxies, this observation supports the idea of an expanding universe. Therefore, the most reasonable conclusion is that the galaxy is moving away from Earth.

Key Concept: Scientific Inquiry, Nature of Science

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion claims that the brightness of stars depends only on their distance from Earth. However, in reality, a star’s apparent brightness (as seen from Earth) depends on both its intrinsic luminosity and its distance from Earth. The Reason states that the intensity of light decreases with the square of the distance, which is correct according to the inverse-square law of light propagation. Hence, while the Reason is scientifically accurate, the Assertion oversimplifies the factors affecting a star’s brightness.

Key Concept: Science Exploration

b) Following a step-by-step process to find answers
[Solution Description]
According to the syllabus, science is defined as a way of thinking, observing, and doing things to understand the world and uncover the mysteries of the universe. The correct option should reflect this joyful exploration process.

Key Concept: Scientific Thinking

c) Guessing there might have been too much water
[Solution Description]
In the scientific method, after observing something (water spilling), we form a hypothesis – a possible explanation. Here, suggesting “maybe there was too much water” represents forming a hypothesis to explain why water spilled from the cooker.

Key Concept: Scientific Method in Daily Life

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that a bicycle repair person checking for a punctured tire is applying the scientific method. This is true because the repair person observes the problem (flat tire), forms a hypothesis (e.g., puncture caused by a nail), and tests it (by inspecting the tire). The reason explains the steps of the scientific method, which aligns with the assertion. Both are true, and the reason correctly explains the assertion.

Key Concept: Daily Life Science

c) Repairing a flat bicycle tyre
[Solution Description]
Repairing a flat bicycle tyre by identifying where the air leaked out follows the scientific method: observation, questioning, hypothesizing the leak source, and testing it.

Key Concept: Scientific Inquiry, Interconnectedness of Science

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that scientific discovery resembles an unending jigsaw puzzle where every new piece raises further questions. This aligns with the syllabus’s explanation that science is a continuous process of learning and inquiry. The reason supports this by stating that scientific understanding changes with new discoveries, reinforcing the idea that knowledge is dynamic and interconnected. Hence, both are true, and the reason correctly explains the assertion.

Key Concept: Life on Earth and Interconnected Ideas

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion correctly states that Earth is the only known planet supporting life, making its protection essential. The reason provides an example of life diversity (seed to plant, caterpillar to butterfly), which indeed shows how natural processes are interconnected, thus validating the need to protect the environment. Therefore, both statements are true, and the reason correctly explains the assertion.

Key Concept: What Will We Explore in This Book?

c) Discovering scientific concepts and phenomena
[Solution Description]
The syllabus clearly states that the book will explore various aspects of science, including life on Earth, food, celestial bodies, and the spirit of inquiry. The book aims to foster curiosity and discovery in science.

Key Concept: Environmental protection, Scientific method

c) Compare bee populations in treated and untreated areas under controlled conditions
[Solution Description]
After forming a hypothesis, the next step is to design and conduct controlled experiments. The scientist should compare bee health in pesticide-exposed and pesticide-free environments while keeping other factors constant.

Key Concept: Biodiversity

c) A tropical rainforest
[Solution Description]
Biodiversity refers to the variety of life in a particular habitat or ecosystem. Tropical rainforests are known to have the highest biodiversity due to their warm climate, abundant rainfall, and diverse plant life, which support a wide range of animal species.

Key Concept: Earth’s Habitability

b) It is located at the perfect distance from the Sun to maintain moderate temperatures.
[Solution Description]
Earth is the only known planet that supports life due to its unique combination of factors such as the presence of water, a suitable atmosphere, and moderate temperatures. These conditions allow for the existence of liquid water, which is essential for life as we know it.

Key Concept: Food and Its Components, Daily Life Applications

c) Using iodine solution to check for a color change.
[Solution Description]
To test for starch, iodine solution can be used. If the food sample turns blue-black when iodine is added, it confirms the presence of starch. This is a common chemical test in science to identify carbohydrates like starch in food.

Key Concept: Food and Its Components

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that food is important for survival and growth, which is true as food provides energy and essential nutrients needed for bodily functions. The reason explains that different foods offer varied nutrients, supporting the assertion by detailing how food contributes to survival and growth through diverse nutrients. Thus, both are true, and the reason correctly explains the assertion.

Key Concept: Materials Around Us

d) Bicycle
[Solution Description]
Many everyday objects consist of more than one material. For example, a mechanical pencil has a plastic body, metal clip, and rubber grip. Among the options provided below, a bicycle is assembled using multiple materials like metal (frame), rubber (tires), and plastic (seat). The other options are typically made of single materials: a rubber eraser (rubber), glass cup (glass), and wooden stick (wood).

Key Concept: States of water, Temperature measurement

d) Assertion is false, but Reason is true.
[Solution Description]
Assertion: When ice is heated, it first melts into liquid water at 0$^\circ$C (melting point) and then boils into steam at 100$^\circ$C (boiling point). Heating does not directly convert ice to steam. Hence, the assertion is false.
Reason: The melting point of ice (0$^\circ$C) and boiling point of water (100$^\circ$C) are distinct under standard conditions. Thus, the reason is also false.
Since both the assertion and reason are false, none of the options fit perfectly. However, based on the most accurate alignment, we conclude that the assertion is false while the reason is true (as per standard understanding, but contextually incorrect here). Therefore, the correct choice is option (d).

Key Concept: Temperature Importance

c) To understand hot and cold conditions
[Solution Description]
Measuring temperature helps us understand weather conditions, predict changes, and analyze phenomena like freezing and boiling of water. Temperature indicates the hotness or coldness of a substance or environment.

Key Concept: Weather Phenomenon

b) Condensation of water vapor in the atmosphere
[Solution Description]
Rain occurs when water vapor in the atmosphere cools and condenses into tiny droplets that form clouds. These droplets combine and fall as rain due to gravity.

Key Concept: Stars

c) Stars
[Solution Description]
The night sky has millions of shining objects called stars. They are celestial bodies that emit light.

Key Concept: Interconnected ideas, Scientific discovery

b) We realize that scientific ideas are all connected.
[Solution Description]
The syllabus states that discoveries reveal interconnectedness among scientific ideas. For example, understanding celestial bodies connects to Earth’s environment and life forms. This holistic view enhances our comprehension of science.

Key Concept: Scientific Method

c) Asking a question
[Solution Description]
The scientific method begins with identifying a problem or asking a question. This step helps frame the inquiry.

Key Concept: Life Processes, Scientific Inquiry

b) Applying different fertilizers to identical plants under the same light and water conditions
[Solution Description]
The syllabus emphasizes curiosity, systematic observation, and controlled experiments to answer scientific questions. Testing multiple fertilizers on identical tomato plants under the same conditions allows for a fair comparison, isolating the variable (fertilizer type) while keeping other factors constant (light, water, etc.). This approach ensures reliable results and aligns with the scientific method discussed in the syllabus.

Key Concept: Scientific Method, Plant Growth

b) Move the plant to a location with more sunlight and monitor growth
[Solution Description]
The scientific method involves several steps: observation, forming a hypothesis, testing the hypothesis through experiments, analyzing results, and drawing conclusions. Here, the student has already observed the issue and formed a hypothesis about insufficient sunlight. The next logical step would be to conduct an experiment to test this hypothesis by ensuring the plant receives adequate sunlight and comparing its growth with another similar plant kept in shade.

Key Concept: Scientific Inquiry

b) Ignoring unexpected results to fit initial expectations
[Solution Description]
The scientific method involves observing a problem, forming a hypothesis, conducting experiments, analyzing data, and drawing conclusions. “Ignoring unexpected results” contradicts the method, as all observations must be considered.

Key Concept: Observation, Hypothesis, Experimentation

b) Place identical bread samples in warm and cold environments and observe mold growth
[Solution Description]
To test the hypothesis that temperature affects mold growth, the students need to control all variables except temperature. They should place identical bread samples in different environments (e.g., warm and cold) and observe the mold growth over time. This ensures that any differences in mold growth are due to temperature and not other factors.

Key Concept: Daily Life Applications

d) Checking why a light bulb is not working
[Solution Description]
The scientific method involves questioning, hypothesizing, testing, and analyzing. An electrician checking why a bulb isn’t working by testing the bulb and switch follows this process.

Key Concept: Scientific Thinking in Daily Life

b) Guessing that overfilling or improper sealing caused the spill
[Solution Description]
Scientific thinking involves forming hypotheses based on observations, such as guessing that overfilling or improper sealing causes the spill.

Key Concept: Steps in the Scientific Method

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, the first step in the scientific method is observing something interesting or not understood. This observation leads to forming a question. So, the assertion (A) that observing something interesting leads to asking questions is correct. The reason (R) correctly explains this by stating that the scientific method starts with observation followed by forming a question. Hence, both are true and Reason correctly explains Assertion.

Key Concept: Scientific Method

b) Move the plant to a sunnier spot and observe
[Solution Description]
The student has already observed the wilting plant and asked a question about it. She has guessed that lack of sunlight might be the cause. According to the scientific method, the next step is to test this guess through an experiment or observation. The best way would be to move the plant to a sunnier spot and observe if it improves.

Key Concept: Scientific Method, Problem-Solving

c) Propose a hypothesis about differences in vegetable properties affecting cooking time.
[Solution Description]
After making an observation, the next step in the scientific method is to formulate a hypothesis—a possible explanation for the observed phenomenon. The chef should consider variables like vegetable density, water content, or size before experimenting.

Key Concept: Observation, Problem-Solving, Scientific Reasoning

d) Ignoring all observations and concluding without any testing.
[Solution Description]
The scientific method involves making observations, forming hypotheses, testing them, and analyzing results. Ignoring all observations contradicts the very first step of the scientific method, which is based on careful observation and questioning.

Key Concept: Scientific Method

b) Observe that the pen has stopped writing
[Solution Description]
The first step in the scientific method is observing something that we find interesting or do not understand. In this case, we observe that the pen has stopped writing.

Key Concept: Scientific Method in Simple Phenomena

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that careful observation is the first step when a pen stops writing, which is true because identifying the issue requires observing the pen’s condition (e.g., checking if the nib is damaged or the ink level is low). The Reason correctly explains that observation is the initial step in the scientific method, leading to forming a question (e.g., “Why did the pen stop?”). Both statements are true, and the Reason logically explains the Assertion.

Key Concept: Application of Scientific Method

b) Following a step-by-step process
[Solution Description]
The electrician follows systematic steps: identifying the problem (non-working bulb), making initial observations (bulb is intact), forming a new hypothesis (problem might be with the switch), and testing it. This shows the iterative nature of the scientific method where one test leads to another until the solution is found.

Key Concept: Scientific Thinking

c) Measure and compare the temperatures of both toasters
[Solution Description]
After making an observation (toast burns faster) and questioning the cause (higher temperature?), the next logical step is to design a test. Maria could use a thermometer to measure and compare temperatures of both toasters when set to the same level – this would constitute an experimental verification of her hypothesis.

Key Concept: Scientific Method, Observation, Hypothesis

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that a student observed differential growth in plants based on light exposure and concluded sunlight is essential for growth. This aligns with the scientific method where observation leads to a hypothesis. The reason explains the steps of the scientific method, which includes observation and hypothesis formation. Here, the reason correctly explains the assertion because the student’s conclusion is derived from following the scientific method.

Key Concept: Scientific Method, Observing

c) Keeping all conditions except sunlight identical for all plants.
[Solution Description]
The most critical step in validating the observation is controlling other variables that could affect plant growth, such as water availability, soil quality, and temperature. Only by keeping these constant can the scientist confidently attribute any changes in plant height to sunlight exposure.

Key Concept: Scientific Method: Observing

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that observation is the first step in the scientific method as it leads to curiosity and questioning, which is true according to the syllabus. The reason given is that keen observation helps scientists formulate questions about natural phenomena, which is also true. Moreover, the reason directly explains why observation is the first step, as it is through observation that questions arise. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Observation Importance

c) It is the foundation for asking questions
[Solution Description]
Observation is important because it leads to questions about phenomena, which is the starting point for any scientific inquiry. Without observation, there would be no questions to investigate.

Key Concept: Scientific Method – Observation and Questioning

c) Ask a question about why the plant grew taller near the window.
[Solution Description]
According to the scientific method, after making an observation (the plant growing taller near the window), the next logical step is to ask a question based on the observation. Questions could include: “Why does the plant grow taller near the window?” or “Does sunlight affect plant growth?” The scientific method emphasizes curiosity-driven questioning after initial observations.

Key Concept: Curiosity, Question Formulation

c) Wonder why it appears, question how sunlight and raindrops interact, explore refraction
[Solution Description]
Scientific questioning should begin with curiosity about observable phenomena. The best approach involves observing the rainbow carefully, then formulating specific questions about how light interacts with water droplets, followed by developing testable explanations rather than accepting surface-level answers or making random guesses.

Key Concept: Scientific Method – Problem-Solving Steps

b) Replace the old batteries with new ones to check if it works.
[Solution Description]
The scientific method involves systematic problem-solving steps: observation (toy car stopped working, old batteries), questioning (“Did the batteries cause the issue?”), hypothesis formation (“Replacing batteries might fix it”), experimentation (replacing batteries), and conclusion. Arun must apply logical reasoning to test his hypothesis through experimentation rather than randomly trying fixes or ignoring the issue.

Key Concept: Scientific Method – Testing Hypothesis

c) Open the pen to check the ink refill
[Solution Description]
After forming the hypothesis that the ink has finished, the next logical step is to test this guess by checking the ink refill. This step confirms or refutes the hypothesis.

Key Concept: Scientific Method – Revising Hypothesis

b) Make another guess, like the ink dried up
[Solution Description]
If the initial hypothesis (ink finished) is proven wrong, the scientific method requires forming a new hypothesis, such as the ink drying up, and testing it further.

Key Concept: Hypothesis formation, Observation

c) Plants stretch towards light and grow taller when deprived of it.
[Solution Description]
The scientist notices a pattern: plants in the dark grow taller. A valid hypothesis should propose a testable explanation for why this happens. One possible explanation is that plants in darkness stretch to reach light (etiolation). This hypothesis can be tested by measuring growth under controlled light conditions.

Key Concept: Application of Scientific Method

c) Checking why a bicycle tyre is flat
[Solution Description]
Activities like solving why a pen stopped writing, checking a flat bicycle tyre, or figuring out why dal spilled from a cooker involve applying the scientific method by observing, hypothesizing, and testing.

Key Concept: Scientific Method – Testing through experiments or observations

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion claims that the scientific method is exclusive to professional scientists, which is incorrect according to the syllabus. The Reason states that anyone following the defined steps is using the scientific method, which aligns with the syllabus examples like a bicycle repair person or an electrician troubleshooting issues.
Therefore, Assertion is false because the scientific method is not limited to professionals, while Reason is true as it correctly describes the universal application of the method.

Key Concept: Scientific Method, Hypothesis Testing

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
In the scientific method, a hypothesis is an educated guess that must be testable through experiments or observations. This is a fundamental requirement for any hypothesis to be scientifically valid. The reason states that the validity of a hypothesis relies on whether it can be confirmed or falsified by empirical evidence. This directly explains why the assertion is true because the ability to test and verify a hypothesis through evidence is central to the scientific method.

Key Concept: Scientific Method – Hypothesis

d) Hypothesis
[Solution Description]
An educated guess or possible explanation for an observed phenomenon is called a hypothesis. Here, the electrician suspects the switch is faulty, which is a hypothesis that can be tested through further investigation.

Key Concept: Application of Scientific Method

c) Anyone who follows its steps
[Solution Description]
The scientific method is not limited to scientists; anyone who follows its steps—even in daily activities like cooking or fixing a bicycle—is applying the scientific method.

Key Concept: Experimental Design, Data Interpretation

c) Accept the results after normalizing scores based on previous performance
[Solution Description]
When analyzing experimental results, baseline differences in groups can significantly impact validity. In proper scientific method, groups should be randomly assigned to minimize pre-existing differences. Here, the prior academic performance acts as a confounding variable. The correct scientific approach would be to either re-randomize groups or statistically adjust for prior grades before concluding anything about the teaching method’s effectiveness.

Key Concept: Curiosity and Observation

c) It leads to asking questions and exploring answers.
[Solution Description]
Curiosity drives the process of asking questions, which is the first step in the scientific method. Without curiosity, there would be no motivation to observe, question, or explore phenomena. The syllabus emphasizes that curiosity is fundamental to observing surroundings and uncovering the secrets of the universe.

Key Concept: Scientific Method, Problem-Solving

b) Keep half the plants in sunlight and half in darkness, measuring growth weekly.
[Solution Description]
To test the hypothesis, the student should design an experiment where one group of plants receives sunlight and another does not, while keeping all other conditions (water, soil type etc.) the same. The growth of both groups should be measured over time to see if sunlight affects growth.

Key Concept: Everyday Science

c) Trying to find out why a light bulb isn’t working
[Solution Description]
The syllabus gives examples like someone cooking wondering why food spilled, or a bicycle repair person finding why a tyre is flat. These show everyday problem-solving using observation and questioning.

Key Concept: Real-World Application, Iterative Testing

d) Check if any pre-prepared ingredient already contained salt
[Solution Description]
The chef should first confirm if the measured salt quantity matched the recipe’s requirement (hypothesis: measurement error). If correct, taste other ingredients (e.g., broth or sauces) to identify hidden salt sources (revised hypothesis: ingredient imbalance). This iterative testing aligns with the scientific method’s core principles of observation, hypothesis, and validation.

Key Concept: Scientific Method Application, Hypothesis Testing

c) Verify if the dough was given enough time to rise before baking
[Solution Description]
The baker has already tested and confirmed that the yeast is active (first hypothesis rejected). The next logical step is to form a new hypothesis based on other possible causes of bread not rising, such as incorrect kneading, insufficient time for dough to rise, or wrong oven temperature. This follows the iterative process of the scientific method where each hypothesis is systematically tested.

Key Concept: Electrical Fault Finding

b) Check outlet → test bulb → examine switch
[Solution Description]
Correct methodology:
1) Verify power source – check if outlet works with another device
2) Examine simplest component – test bulb in another fixture
3) Proceed to check wiring/switches only if above don’t solve it
This follows from simple to complex diagnosis.

Key Concept: Hypothesis Formation, Observation

c) Test the bulb in another socket, check power supply, and inspect the switch step-by-step
[Solution Description]
The electrician should systematically test possible causes based on observation and elimination. First, they can check if the bulb is faulty by replacing it with a known working bulb. If it still doesn’t light up, they can check the power supply or connect another device to the same socket to verify if electricity is reaching the socket. Finally, they can inspect the switch for defects. This methodical approach ensures accurate problem identification without assumptions.

Key Concept: Scientific Method

c) They ask others to help them out
[Solution Description]
The syllabus states that scientists often work together in teams and suggests asking friends for help when you can’t find answers alone.

Key Concept: Collaboration in Science, Hypothesis Testing

b) Assign roles (e.g., timer, recorder) to synchronize data collection and analysis
[Solution Description]
Collaborative science involves dividing tasks logically among team members to ensure comprehensive data collection. The group can assign roles such as measuring initial ice cube masses, recording temperature changes, timing the melting process, and noting environmental conditions like room temperature. By pooling observations and analyzing results together, they can draw conclusions about heat conductivity differences between metal and wood.

Key Concept: Curiosity in Science, Scientific Method, Collaboration

c) It motivates questioning and exploration of the unknown
[Solution Description]
Curiosity drives scientists to ask questions about natural phenomena, leading to exploration and discovery. Without curiosity, there would be no motivation to investigate how things work or uncover new knowledge. It fuels hypothesis formation and experimentation. Additionally, collaboration among scientists worldwide helps validate findings and accelerate discoveries.

Key Concept: Scientific Method

c) Observing and wondering about something
[Solution Description]
The first step in the scientific method is to observe something interesting or puzzling that leads to a question.

Key Concept: Collaboration in Science, Problem-Solving, Shared Discovery

c) It combines diverse skills and accelerates discoveries
[Solution Description]
Collaboration pools diverse expertise, allowing complex problems to be tackled from multiple perspectives. Scientists can cross-validate findings, reducing errors. Joint efforts often lead to faster breakthroughs, as seen in global projects like the Large Hadron Collider. Shared curiosity fosters innovation.

Key Concept: Concept: Scientific Method

b) Asking a question based on observation.
[Solution Description]
The scientific method begins with observation and curiosity, leading to questions about natural phenomena. According to the syllabus, we first observe something interesting or puzzling and then ask questions about it.

Key Concept: Curiosity and Scientific Inquiry

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that curiosity is essential for scientific inquiry as it initiates questioning and answer-seeking, which aligns with the syllabus content emphasizing curiosity as the starting point of science. The reason explains that the scientific method starts with observation (rooted in curiosity), followed by hypothesis and experimentation, which directly supports the assertion. Therefore, both are true, and the reason correctly explains the assertion.

Key Concept: Curiosity in Scientific Process, Role of Questions

c) Ask new questions about why and how the light affects plant growth.
[Solution Description]
The scientific method starts with observation and curiosity. After noticing that plants grow taller under specific light, the scientist should ask, “Why does this happen?” or “How does this light affect growth?” This leads to formulating a hypothesis, which is essential for further experimentation.

Key Concept: Scientific method, Curiosity

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion describes the fundamental steps of the scientific method, which is indeed universal in science. The reason explains why this structured approach is beneficial—it ensures systematic, repeatable, and reliable results, leading to better understanding. Both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Curiosity and Scientific Method

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that science helps us understand the world through curiosity and exploration, which aligns with the syllabus content emphasizing the role of curiosity in science. The reason explains that curiosity leads to asking questions, which is indeed the initial step in the scientific method as described in the syllabus. Both statements are true, and the reason correctly explains the assertion.

Key Concept: Curiosity and Observation

c) Ask why some leaves change color in autumn while others do not
[Solution Description]
The first step in scientific inquiry is observation, followed by forming a question. Here, the child has already observed the phenomenon. Next, they should ask “Why do some leaves change color in autumn while others do not?” This aligns with the syllabus concept of observing surroundings and asking questions out of curiosity.

Key Concept: Efficiency in Collaborative Work

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
To verify:
1. **Assertion (A)** states that increasing the number of equally efficient workers reduces time taken. This assumes that adding more workers scales efficiency linearly, which is only true if workers share tasks without dependency delays or inefficiencies.
2. **Reason (R)** claims that time taken is inversely proportional to the number of workers (if efficiencies are equal). This is mathematically correct under ideal conditions ($T \propto \frac{1}{N}$ where $T$ = time, $N$ = workers).
However, Assertion (A) uses “always,” ignoring real-world constraints like coordination overhead or diminishing returns, making it an overgeneralization. Thus, while Reason (R) is true in theory, it does not fully explain Assertion (A)’s definitive claim.

Key Concept: Scientific Method

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that a bicycle repair person trying to find out why a tyre is flat is following the scientific method. This is true as it involves observing the problem (flat tyre), questioning the cause, guessing possible reasons (like puncture or valve issue), testing (checking for leaks), and analyzing results. The Reason explains the steps of the scientific method (observe, question, guess, test, analyze), which matches the process described in the Assertion. Hence, both Assertion and Reason are true, and Reason correctly explains the Assertion.

Key Concept: Scientific Method Application

c) Test each suggestion separately in a systematic way
[Solution Description]
The scientific method requires testing one variable at a time while keeping others constant. Working together effectively means systematically testing each hypothesis separately rather than making multiple changes simultaneously. They should choose one variable to test first (e.g., just change watering schedule while keeping light and soil same), observe results, then proceed to test other variables if needed.

Key Concept: Collaboration, Hypothesis Formation

c) Standardize measurement protocols and reconcile data inputs
[Solution Description]
Teams should first align methodologies by comparing input parameters (e.g., soil sample sizes). Next, they should jointly identify variables causing divergence—such as local vegetation types omitted in some models. By creating a unified experimental framework and sharing raw datasets, they can isolate modeling discrepancies.

Key Concept: Scientific Inquiry in Daily Life

b) Asking questions and investigating
[Solution Description]
The electrician is identifying a problem (the bulb not working), questioning why it happened, and investigating possible causes, which reflects the process of scientific inquiry.

Key Concept: Collaborative Nature of Scientific Discovery

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that scientists work in teams for better problem-solving. This is true because collaborative efforts combine diverse expertise. The reason explains that unique perspectives and skills enhance efficiency in solving complex questions. Here, the reason directly supports why teamwork is beneficial in science, making it the correct explanation of the assertion.

Key Concept: Teamwork, Problem-Solving

b) It ensures each task is handled by the most skilled member
[Solution Description]
Teamwork leverages individual strengths to improve overall efficiency and quality. One student’s observational skills gather accurate data, another’s recording ensures systematic documentation, and the third’s analytical skills derive meaningful conclusions. Combined efforts minimize errors and enhance depth and accuracy of the project.

Key Concept: Teamwork in Science

c) It makes discoveries more effective and enjoyable.
[Solution Description]
Collaboration allows scientists to combine their knowledge and skills, making problem-solving more effective and enjoyable. According to the syllabus, working together helps tackle complex problems and makes discoveries more fruitful.

Key Concept: Collaboration, Scientific Method

b) Greater reliability of findings through peer validation
[Solution Description]
Collaboration in science allows pooling diverse expertise, resources, and perspectives, leading to comprehensive and faster solutions. Teamwork helps tackle complex problems like environmental studies that require large-scale data collection and varied skill sets. It also ensures validation of results through peer reviews and reduces biases.

Key Concept: Scientific Method

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion (A) states that science helps uncover mysteries through a systematic process, which is true as described in the syllabus (e.g., “Science is not just about memorising facts…”). The reason (R) describes the steps of the scientific method (asking questions, testing guesses), which aligns with the syllabus (“This is exactly how Science works!”). Moreover, R correctly explains A because the scientific method is the structured approach science uses to explore the world. Therefore, both are true, and R explains A.

Key Concept: Scientific Method

c) Presence or absence of sunlight
[Solution Description]
The independent variable is the factor intentionally changed by the scientist to observe its effect. Here, the amount of sunlight is deliberately varied (one plant in sunlight, another in darkness), making it the independent variable. Water and soil type are controlled variables, and plant growth is the dependent variable.

Key Concept: Scientific Process

c) Guessing and testing repeatedly
[Solution Description]
The syllabus describes the scientific method as a step-by-step process to find answers. For example, if a pen stops writing, one might guess the ink is finished and test it. If not, another guess is made and tested again.

Key Concept: Conceptual complexity, Scientific method

c) Repeat the experiment with stricter controls and compare results again.
[Solution Description]
Scientific disputes are resolved through rigorous re-examination of methods, peer review, and additional experiments. Conflicting results indicate possible flaws in experimental setup, interpretation, or variables. The scientific method emphasizes verification through replication, critical analysis, and discussion among peers. Therefore, the best approach involves revisiting the experimental procedure rather than disregarding either conclusion without evidence.

Key Concept: Collaboration in Science

d) By collaborating in teams worldwide
[Solution Description]
Scientists usually work in teams and collaborate with others across the world. The passage highlights that science is rarely done alone and teamwork makes discovering things more fun and productive.

Key Concept: Science as Continuous Exploration

d) Assertion is false, but Reason is true.
[Solution Description]
The assertion claims that science does not change our existing understanding, while the reason states that scientific discoveries refine or replace old ideas with new evidence. According to the syllabus, “New discoveries often change our understanding of the world.” Therefore, the assertion is false because science does update our knowledge, but the reason is true as discoveries lead to revised understandings.

Key Concept: Scientific Method, Curiosity

d) Assertion is false, but Reason is true.
[Solution Description]
The Assertion claims that the scientific method is limited to professional scientists in laboratories, which is false. The Reason states that following such a process is exclusive to trained scientists, which is also false. As the syllabus explains, anyone who follows the scientific method—whether a bicycle repair person or someone cooking food—is working like a scientist. The method is not restricted to professionals or labs. Both statements are incorrect, but since the Reason attempts to justify the Assertion, it follows the structure of an explanation even though both are wrong.

Key Concept: Scientific Method Application

b) You observe the plant’s location has less sunlight than others, move it to a sunnier spot, wait two weeks, then check if it flowers as control.
[Solution Description]
The complete scientific method involves:
1) Observing the non-flowering plant,
2) Asking why it’s not flowering,
3) Making hypotheses (e.g., insufficient sunlight, wrong soil pH),
4) Testing each hypothesis systematically (moving plant to sunnier spot, testing soil),
5) Analyzing results to find which change caused flowering.
The correct option must show this full process with logical sequence and verification.