Section A
- b
- b
- a
- b
- b
- b
- b
- a
- a
- b
Section B
11. An assumption is a deliberate choice made while simplifying a system. For example, air resistance may be ignored while studying the basic motion of a falling object.
12. The colour of a bicycle normally has no significant effect on the time needed to travel a given distance, so it can be ignored in a simple model.
13. An observation is information obtained by noticing or measuring something. A prediction is a reasoned expectation about what may happen under specified conditions.
14. Estimating the amount of rice required by a family for a month is a situation where an approximate answer can be useful.
15. Any two: physics, chemistry, biology, earth science.
Section C
16. Scientific terms, symbols and units must have clear meanings so that scientists can communicate observations and results without ambiguity. Precise language also makes experiments and calculations reproducible.
17. A scientific theory is supported by evidence, repeated testing and critical examination. It explains observed patterns and can make predictions. Therefore, it is very different from an unsupported guess.
18. Standard units ensure that the same measurement means the same thing everywhere. They make results easier to compare, reduce conversion errors and support reliable scientific communication.
19. Scientists should re-examine the model, assumptions, measurements and conditions of the experiment. A mismatch is useful because it may reveal a limitation or suggest that the explanation needs improvement.
Section D
20.
a)
Steps = 100 × 90
= 9,000 steps
b) The walking rate is an estimate and may not remain exactly 100 steps per minute.
c) Walking speed, rest periods, different activities and inaccurate counting could change the actual number.
21.
a) Important factors include the speed of the ball and its direction of motion. The mass of the ball may also be relevant.
b) The colour of the ball and brand of the bat can be ignored in a simple model.
c) They have little or no significant effect on the specific question being studied, so ignoring them keeps the model simpler.
Section E
22.
- Law: Describes a regular pattern observed in nature. Example: a scientific law may describe how a physical quantity behaves under specified conditions.
- Theory: Provides an evidence-based explanation for why or how a pattern occurs. Atomic theory explains aspects of how matter is organised.
- Principle: A broad idea that helps explain or analyse a situation. The principle of conservation of energy is used in many physical situations.
A theory is not a guess, and these scientific ideas remain open to refinement when new evidence appears.
23. Mathematics gives science a precise way to express relationships between quantities. Symbols and equations can show how one quantity changes when another changes.
For example, distance and time can be related to describe motion. Mathematical relationships also allow scientists to make predictions and check whether measurements are consistent with a proposed model.
Thus, mathematics is not merely a tool for calculation; it is a language that helps scientists reason clearly about patterns and relationships.