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Exploration: Entering the World of Secondary Science: questions with answers

Class 9 Science, Chapter 1 (NCERT). 15 questions by concept. Open “Show answer” for the answer and why.

How to teach this chapter · Common misconceptions & worked visual for this chapter

Evidence, scientific ideas, and testable predictions

Question 1

Which measurement would best test the prediction that wind helps wet clothes dry faster under otherwise similar conditions?

  1. (a)Colour of the wet clothes
  2. (b)Drying time with and without wind
  3. (c)Confidence in the prediction
  4. (d)Number of people repeating the prediction
Show answer

(b) Drying time with and without wind

Compare drying times for identical clothes with equal starting wetness, with and without wind. Keep other conditions similar, including temperature and sunlight. Shorter drying time with wind would support the prediction.

Question 2

What makes a rain prediction scientific?

  1. (a)Dark clouds, taken as proof
  2. (b)Measured conditions matching a pattern seen before recent rain
  3. (c)Repetition of the statement
  4. (d)The speaker's strong feeling
Show answer

(b) Measured conditions matching a pattern seen before recent rain

A scientific prediction rests on measurements and on a pattern seen before earlier rains. A strong feeling, clouds treated as proof, or a repeated statement offer no such evidence.

Question 3

What support is missing from a prediction based only on a strong feeling?

  1. (a)Knowledge of the event's final outcome
  2. (b)A question with a yes-or-no answer
  3. (c)Measurable evidence or a relevant past pattern
  4. (d)No further support
Show answer

(c) Measurable evidence or a relevant past pattern

A strong feeling provides no evidence about what will happen. A scientific prediction needs support from measurable evidence or a relevant past pattern.

Scientific models and relevant details

Question 4

A simple model asks whether a struck cricket ball will cross the boundary before hitting the ground. Which detail is relevant?

  1. (a)The brand of the bat
  2. (b)Every visible detail, because a model must copy the whole scene
  3. (c)The speed and direction in which the ball is hit
  4. (d)The colour of the ball
Show answer

(c) The speed and direction in which the ball is hit

The model keeps details that affect whether the ball reaches the boundary, such as speed and direction. Brand and colour do not answer that question.

Question 5

A simple model of a struck cricket ball has to answer one question: does the ball cross the boundary? Which detail of the ball can the model ignore?

  1. (a)The speed of the ball
  2. (b)The colour of the ball
  3. (c)No detail can be ignored
  4. (d)The direction in which the ball is hit
Show answer

(b) The colour of the ball

The model only has to decide whether the ball crosses the boundary. The colour of the ball has no effect on that. The speed and the direction decide how far the ball travels. So a simple model leaves the colour out and keeps only what the question needs.

Question 6

What decides whether a detail belongs in a model?

  1. (a)The question the model is designed to answer
  2. (b)A rule that every detail must be included
  3. (c)How easy the detail is to observe
  4. (d)A fixed list of details that every model needs
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(a) The question the model is designed to answer

A model is built to answer a particular question. That question decides which details are kept and which are left out. So a detail kept in one model can be ignored in another.

Precise scientific language, symbols, units, and mathematics

Question 7

Why does science give precise meanings to familiar words such as force, work, cell, and reaction?

  1. (a)Only to make scientific writing sound more difficult
  2. (b)Because their everyday meanings are always identical to their scientific meanings
  3. (c)So observations and ideas can be communicated clearly and unambiguously
  4. (d)So each scientist can choose a private meaning
Show answer

(c) So observations and ideas can be communicated clearly and unambiguously

Scientific communication depends on shared, specific meanings. Familiar everyday usage may be broader or different and cannot simply be substituted.

Question 8

What error comes from always using the everyday meaning of 'work' in science?

  1. (a)Using a word instead of a numerical symbol
  2. (b)Ignoring the term's agreed scientific meaning
  3. (c)Using the same scientific meaning for everyone
  4. (d)No error
Show answer

(b) Ignoring the term's agreed scientific meaning

The word 'work' has an agreed scientific meaning that differs from its everyday meaning. Always using the everyday meaning ignores this distinction.

Question 9

Before selecting an equation for a scientific situation, what should a learner do first?

  1. (a)Ignore the meaning of the quantities and focus only on arithmetic
  2. (b)Memorise an equation and substitute every number immediately
  3. (c)Understand the situation and identify the relevant quantities
  4. (d)Assume any equation with the right symbols will describe the situation
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(c) Understand the situation and identify the relevant quantities

Mathematics helps after the situation and its relevant quantities are understood. This lets an equation express the relationship that actually matters.

Estimation and checking reasonableness

Question 10

Which set of quantities is needed to estimate the volume of air breathed in one day?

  1. (a)Breaths per minute, minutes per day, and volume of air per breath
  2. (b)Breaths per minute and the colour of a balloon
  3. (c)Minutes per day and the price of a balloon
  4. (d)Only a number chosen because it seems large
Show answer

(a) Breaths per minute, minutes per day, and volume of air per breath

A daily volume is built from how often breathing occurs, how long it continues, and how much air is in each breath. These factors give a transparent chain of reasoning.

Question 11

A rough estimate uses 20,000 breaths per day and 0.5 litre per breath. About how much air is breathed in one day?

  1. (a)20,000 litres
  2. (b)0.5 litre
  3. (c)10,000 litres
  4. (d)40,000 litres
Show answer

(c) 10,000 litres

Multiply the approximate number of breaths by the approximate volume per breath. 20,000 × 0.5 is about 10,000 litres.

Question 12

Why is the daily-breath calculation a reasoned estimate rather than a random guess?

  1. (a)It states reasonable approximate inputs and shows how the relevant quantities are combined.
  2. (b)The multiplication makes every input and result exact.
  3. (c)An estimate should hide its assumptions so only the result is visible.
  4. (d)Any rounded number is automatically a scientific estimate.
Show answer

(a) It states reasonable approximate inputs and shows how the relevant quantities are combined.

The assumptions about breathing rate and volume are explicit, and the calculation connects them to the requested daily total. Approximation does not remove the need for reasoning.

Science as connected, human, and critical inquiry

Question 13

What should you ask about a claim that is shared widely online?

  1. (a)How many people have shared it
  2. (b)Whether it is about technology rather than a school experiment
  3. (c)What evidence supports it, and can it be tested
  4. (d)Whether a professional scientist made it
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(c) What evidence supports it, and can it be tested

Scientific thinking asks what evidence supports a claim and whether the claim can be tested. How many people shared the claim, and whether a scientist made it, are not evidence. These habits of questioning are useful in everyday life, not only in a laboratory.

Question 14

What does scientific thinking give someone who stops studying science after Grade 10?

  1. (a)Certainty that a first explanation is final
  2. (b)Recall of textbook facts only
  3. (c)Freedom from questioning everyday claims
  4. (d)Critical evaluation of information and of surrounding technology
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(d) Critical evaluation of information and of surrounding technology

Scientific habits let a person question information, look at the evidence, and make sense of the technology around them. That value stays even when formal science study ends.

Question 15

Which response shows scientific thinking in an ordinary daily decision?

  1. (a)Check relevant evidence, make a reasoned decision, and revise it if better evidence appears.
  2. (b)Choose a conclusion first and ignore observations that disagree with it.
  3. (c)Assume scientific reasoning does not apply outside laboratories.
  4. (d)Use the most repeated opinion and do not question it.
Show answer

(a) Check relevant evidence, make a reasoned decision, and revise it if better evidence appears.

Scientific thinking is evidence-guided and open to correction. It is a transferable way of reasoning in daily life.

Common misconception in Exploration: Entering the World of Secondary Science

Open full misconception guide →

Can one seedling per group settle an experiment?

Wrong

Fertiliser makes seedlings grow faster because my one fertilised seedling grew more than my one untreated seedling.

Why it feels right. I attribute the whole difference to the treatment.

Right

Compare multiple seedlings in each group to account for differences between individuals.

Worked example

40 similar seedlings
Randomly split into two groups
Group A · 20
Same light, soil and water→Add fertiliser→Measure growth
Group B · 20
Same light, soil and water→No fertiliser→Measure growth
The treatment is assigned to groups. Comparing variation within groups helps separate the treatment from individual differences.
  1. Randomly assign 40 similar seedlings to two groups of 20.
  2. Keep light, soil and watering comparable and give fertiliser to one group.
  3. Compare the typical growth and the spread within each group.