Short Answer Type Questions
Ques 1: What is a scientific model? Give one example.
Ans: A scientific model is a simplified way of looking at a real system that focuses only on what is most important for a given question. Building such models involves making assumptions and deliberately ignoring certain details. For example, in physics, a moving car may be represented as a single point to study its motion without unnecessary complexity.
Ques 2: Why does science use a shared language of specific terms, symbols, and units?
Ans: Science uses a shared language so that scientists across the world can describe observations, compare results, and build ideas together clearly and without confusion. Words used in everyday life, such as force, work, cell, or reaction, have very specific meanings in science. Quantities like mass, velocity, and force are represented by symbols like m, v, and F, each associated with a defined unit.
Ques 3: What is the difference between a scientific law and a scientific theory?
Ans: A law usually describes a regular pattern observed in nature, often expressed using words or mathematical relationships. For example, Newton’s laws of motion explain the jerk felt when a bus stops suddenly. A theory goes a step further and provides an explanation of why those patterns occur, usually based on evidence gathered over time. For example, the atomic theory explains how molecules are formed.
Ques 4: Why is making assumptions while building a scientific model not considered a mistake?
Ans: Making assumptions while building a model is not a mistake because it is done on purpose to keep things simple enough, while still allowing us to find answers to what we are looking for. For example, when studying the motion of a falling object, air resistance may be neglected to understand the basic effect of gravity. These choices help focus only on what is most important for a given question.
Ques 5: What are scientific principles? Give one example from daily life.
Ans: Principles are broad ideas that help us make sense of situations in science. They are general guidelines that apply across many different circumstances. For example, the principle of conservation of energy can be applied when climbing up the stairs, where the energy put in by the person is converted into potential energy gained by the body.
Ques 6: What is the role of mathematics in science? Is it only about finding numerical answers?
Ans: Mathematics in science is not just about finding numerical answers – it is a language that helps us think more clearly about the world. Mathematical expressions are used to describe rates of chemical reactions, patterns of population growth, or changes in energy within a system. Learning to use mathematics in science means understanding the situation first, identifying relevant quantities, and then using mathematical relationships to reason carefully.
Ques 7: Why is it important to use standard international units (SI units) in science?
Ans: Using standard international units is important because it allows scientific results to be compared across the world and ensures fairness in daily life and trade. Measurements are based on agreed international standards, not local objects or opinions. A real-world example is a passenger aircraft that ran out of fuel mid-flight because the ground crew used pounds per litre instead of kilograms per litre, causing the aircraft to be about 15,000 litres short of fuel.
Ques 8: What are scientific predictions? Are they the same as guesses?
Ans: Scientific predictions are reasoned expectations about what will happen under new or different conditions, based on well-established laws, theories, and models. They are not guesses – they are carefully thought-out conclusions based on evidence. For example, using ideas about motion, we can predict how far a kicked football will travel, and using biological principles, we can predict how one’s breathing would change while running.
Ques 9: Why is the ability to make predictions considered one of the greatest strengths of science?
Ans: The ability to make predictions is a great strength of science because it allows us to anticipate what will happen under new or different conditions, even before performing an experiment. When predictions match observations, confidence in the underlying science grows. More importantly, when predictions do not match, scientists re-examine their assumptions and models, which drives further exploration and a deeper understanding of the world.
Ques 10: What is estimation in science and why is it a useful skill?
Ans: Estimation is the process of making a rough approximate calculation to check whether an answer is reasonable or impossible, without finding an exact value. It is a useful skill because it helps build intuition, detect errors, and develop confidence in thinking. For example, estimating that a person breathes roughly 10,000 litres of air per day gives a reasonable picture without needing precise measurements, and exact values are not always necessary in the early stages of reasoning.
Ques 11: What do the magnifying glass and compass on the textbook pages symbolise?
Ans: The magnifying glass symbolises careful observation – noticing patterns and paying attention to what might otherwise be missed. The compass reminds us that exploration also needs direction – choosing appropriate models, asking the right questions, and knowing the limits of where our ideas apply. Together, they represent that exploration in science is not wandering aimlessly, but trying to make sense of our world with care and purpose.
Ques 12: Why does science not have fixed boundaries between its branches like physics, chemistry, biology, and earth science?
Ans: Science does not have fixed boundaries between its branches because the natural world itself does not have such divisions – these are made only to help organise knowledge. Most real-world problems, such as understanding climate change, developing medicines, or designing sustainable technologies, require ideas from several disciplines together. For example, understanding how a surgical mask works requires concepts from physics, chemistry, biology, and mathematics all at once.
Long Answer Type Questions
Ques 1: What is a scientific model? Why does science use models to study the natural world? Explain with examples from at least two different branches of science.
Ans: The natural world is complex, and studying it in full detail is often impossible. To make sense of this complexity, science uses models – simplified ways of looking at real systems that focus only on what is most important for a given question.
(i) Need for Models: Building models involves making assumptions and deliberately ignoring certain details. These choices are not mistakes; they are done on purpose to keep things simple enough while still allowing us to find answers.
(ii) Examples from Different Branches: In physics, a moving car may be represented as a single point so that its motion can be studied without worrying about its shape or colour. In chemistry, atoms and molecules are drawn as spheres and bonds, making it easier to study their interactions. In biology, when studying how the heart pumps blood, many individual cells are ignored so that the organ can be understood as a functioning system. In earth science, the Earth may be treated as a smooth sphere layered into distinct regions to study broad geographical patterns.
(iii) What to Include and Ignore: In the cricket ball example, factors like the mass of the ball and direction of the hit matter, while the colour of the ball or brand of the bat can be ignored in a simple model. This shows that what we include and what we ignore depends entirely on the question we are trying to answer.
(iv) Growing Complexity: As we build more and more complex models, we add extra details for greater accuracy. These are not fixed structures but tools that evolve with our understanding.
Ques 2: Distinguish between a law, a theory, and a principle in science. Explain why scientific theories are reliable even though they are always open to change.
Ans: In science, the terms law, theory, and principle have specific meanings that are different from their everyday use.
(i) Scientific Law: A law usually describes a regular pattern observed in nature, often expressed using words or mathematical relationships. For example, Newton’s laws of motion explain the jerk felt when a bus stops suddenly. A law describes what happens but does not necessarily explain why it happens.
(ii) Scientific Theory: A theory goes a step further and provides an explanation of why those patterns occur, based on evidence gathered over time. For example, the atomic theory explains how molecules are formed. In science, a theory does not mean a guess or an untested idea – it is an explanation based on careful testing and critical examination.
(iii) Scientific Principle: Principles are broad ideas that help us make sense of a given situation. For example, the principle of conservation of energy can be applied when climbing stairs, where energy input is converted into potential energy gained.
(iv) Why Theories are Reliable Despite Change: Scientific theories are always open to improvement and often change as new evidence becomes available. This openness to being corrected is not a weakness – it is science’s greatest strength. When predictions do not match observations, scientists do not reject ideas based on opinion or belief, but only on evidence. No scientific theory is ever final, and none is beyond question. This careful and self-correcting process is precisely what makes science reliable and trustworthy over time.
Ques 3: What is the role of predictions in science? How do scientific predictions differ from ordinary guesses? Explain how predictions help drive further exploration.
Ans: One of the most remarkable strengths of science is its ability to make predictions. Scientific predictions are very different from ordinary guesses, and they play a powerful role in the progress of science.
(i) What are Scientific Predictions: When laws, theories, and models are well established, they allow us to anticipate what will happen under new or different conditions – before we can perform an experiment, and in many cases even if we cannot perform an experiment at all.
(ii) Examples of Predictions: Using ideas about motion, we can predict how far a kicked football will travel. Using knowledge of chemical reactions, we can estimate how much carbon dioxide will be produced. Using biological principles, we can predict how one’s breathing would change while running.
(iii) Not Guesses but Reasoned Expectations: Predictions are not guesses – they are based on evidence and careful thinking. For example, when Varsha says “It will rain this afternoon because the clouds look dark,” a scientific approach would ask measurable questions such as what was the humidity today, what is the wind speed and direction, and was the sky condition similar the last time it rained. These questions look for measurable data and past patterns, going far beyond a simple observation.
(iv) Role in Further Exploration: When predictions match observations, confidence in the underlying science grows. More importantly, when they do not match, scientists re-examine their assumptions, models, or measurements. In this way, prediction is a powerful tool that drives further exploration and a deeper understanding of the world.
Ques 4: Why is mathematics important in science? How does it help in expressing and testing scientific ideas? Give examples to support your answer.
Ans: Mathematics plays a vital and indispensable role in science. It is not simply a tool for calculation – it is a language that helps us think more clearly and precisely about the world.
(i) Mathematics as a Language: An equation is not just a calculation tool; it is a compact statement about how certain things are related. For example, describing motion using quantities such as distance, time, and velocity allows us to answer questions about where an object will be at a later moment, which cannot be answered by words alone.
(ii) Expressing Relationships Clearly: Mathematical expressions are used to describe rates of chemical reactions, patterns of population growth, and changes in energy within a system. These relationships, once expressed mathematically, can be tested, verified, or disproved through experiments.
(iii) Symbols and Units: Science uses a shared language of specific terms, symbols, and units. Quantities like mass, velocity, and force are represented by symbols like m, v, and F, each associated with a defined unit, allowing scientists across the world to communicate and compare results without confusion.
(iv) Not About Memorising Equations: Learning to use mathematics in science means understanding the situation first, identifying relevant quantities, and then using mathematical relationships to reason carefully. When you focus first on understanding the situation and the quantities involved, equations feel like helpful guides rather than obstacles.
(v) Real-World Consequence: The importance of correct units was demonstrated when a passenger aircraft ran out of fuel mid-flight because the ground crew used pounds per litre instead of kilograms per litre, leaving the aircraft about 15,000 litres short. Using standard SI units everywhere avoids such dangerous errors.
Ques 5: Explain why science is described as a human activity and not just a collection of facts. What habits of thinking does the study of science develop, and why are these valuable beyond the classroom?
Ans: Science is far more than a collection of facts, equations, or experiments. It is a human activity shaped by curiosity, creativity, collaboration, and careful questioning.
(i) Science as a Human Activity: Science grows as people ask questions, test ideas, share results, and learn from mistakes. It develops over time through the work of many individuals across different cultures and generations. It is not a fixed body of knowledge but an ongoing, evolving process of inquiry.
(ii) Openness and Self-Correction: No scientific theory is ever final, and none is beyond question. When predictions do not match observations, scientists re-examine their assumptions based on evidence, not opinion. This openness to being corrected by nature itself is what has allowed science to help us understand the world we live in.
(iii) Habits of Thinking Developed by Science: Science develops careful observation – noticing patterns and paying attention to what might otherwise be missed. It develops estimation and approximate reasoning – making rough calculations to check whether a result is reasonable without needing exact values. It also develops critical evaluation, as shown when the viral claim that food becomes harmful during a solar eclipse can be disproved simply by asking what physical, chemical, or biological change actually occurs during an eclipse.
(iv) Value Beyond the Classroom: Even if a student does not choose to study science beyond Grade 10, scientific thinking will be very important in whatever they do. It helps in understanding the technology that surrounds us, evaluating information critically, and making sense of the world we live in. Science invites us not only to learn about the world, but also to learn how we are trying to understand it – and that is a skill valuable in every walk of life.