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Class 9 Exploration: Entering the World of Secondary Science worksheet
CBSE Science. Models, units and symbols, laws, theories and principles, predictions, estimation, testing claims. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
A person breathes about 17 times a minute, taking in about 0.6 litre of air each time. Roughly how much air is breathed in a day? Choose the best estimate.
- about 100,000 litres
- about 1,000,000 litres
- about 1,000 litres
- about 10,000 litres
Answer
(d) about 10,000 litres
17 × 0.6 × 1,440 minutes = 14,688 litres, which is about 10,000 litres
- 2.
"Every object attracts every other object with a force." This is best described as:
- a law
- a theory
- a principle
- a guess
Answer
(a) a law
It describes a regular pattern (the universal law of gravitation).
- 3.
The SI unit of frequency is:
- watt (W)
- second (s)
- kilogram (kg)
- hertz (Hz)
Answer
(d) hertz (Hz)
Section B · short answer
- 4.
People blink about 20 times a minute while awake, and are awake about 16 hours a day. Roughly how many times do they blink in a day? Show your working and round to one non-zero digit (like 30,000).
Answer
about 20,000 blinks
20 × 60 × 16 = 19,200
- 5.
Convert 6.6 km into m.
Answer
6,600 m
1 km = 1,000 m
Section C · long answer
- 6.
Meera wants a rough answer. A resting heart beats about 84 times a minute. Roughly how many times does it beat in a day? (a) Write the calculation. (b) Round it to one non-zero digit. (c) Why is a rough estimate useful here?
Answer
(a) 84 × 60 × 24 = 120,960; (b) about 100,000 beats; (c) it quickly shows the size of the answer and helps catch big mistakes
Fresh sheets for your child
In the app, every Exploration: Entering the World of Secondary Science sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
Coming soon for Android and iPhone.