CBSE Class 8 Science Chapter 1: Exploring the Investigative World of Science — Assertion & Reason
CBSE Class 8 Science Assertion & Reason
Expert crafted · Instant PDF download · 2026-27
The following Assertion and Reason questions are based on Chapter 1: Exploring the Investigative World of Science from the NCERT Class 8 Science textbook Curiosity. Each question has four options — read both the Assertion (A) and Reason (R) carefully before selecting your answer.
How to attempt Assertion & Reason questions:
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion & Reason Questions
1
Assertion (A): Scientific investigation involves more than just looking at something and asking simple questions.
Reason (R): Investigation requires asking focused questions, designing simple experiments, and using observations to improve understanding.
Reason (R): Investigation requires asking focused questions, designing simple experiments, and using observations to improve understanding.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Science in Grade 8 moves beyond simple wonder into systematic investigation, where targeted questions and thoughtful experiments help uncover facts[cite: 24, 25].
2
Assertion (A): The kite symbol in the textbook reminds us to stay grounded in real observations.
Reason (R): The root symbol symbolises the deep, solid foundation of knowledge that keeps us connected to our environment.
Reason (R): The root symbol symbolises the deep, solid foundation of knowledge that keeps us connected to our environment.
Answer: (d)
A is false, but R is true. The root symbol represents the solid foundation of knowledge [cite: 30], while the kite symbol reminds us that curiosity and ideas must take flight to explore the unknown[cite: 31, 32].
3
Assertion (A): All microorganisms present around us are invisible helpers that produce medicines and help digest food.
Reason (R): Some microbes can be harmful and cause infections in our bodies.
Reason (R): Some microbes can be harmful and cause infections in our bodies.
Answer: (d)
A is false, but R is true. While many microbes are indeed invisible helpers for digestion and medicines, not all of them are beneficial; some are harmful and cause infections[cite: 43].
4
Assertion (A): Electric current can be used to keep us warm during winters.
Reason (R): Electric motors and machines function due to the heating effect of electric current.
Reason (R): Electric motors and machines function due to the heating effect of electric current.
Answer: (c)
A is true, but R is false. We depend on the heating effect of electric current to stay warm, but motors and machines function due to the magnetic effect of electric current, not the heating effect[cite: 48].
5
Assertion (A): A strong pressure difference in the air can lead to strong winds and cyclones.
Reason (R): The movement of air is dictated by the concepts of force and pressure.
Reason (R): The movement of air is dictated by the concepts of force and pressure.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The distribution of force and pressure decides how air moves; a small difference creates a gentle breeze, while a stronger pressure difference can lead to violent cyclones[cite: 52, 53].
6
Assertion (A): In solid materials, particles can move around freely just like in gases.
Reason (R): Everything around us is made of tiny particles.
Reason (R): Everything around us is made of tiny particles.
Answer: (d)
A is false, but R is true. Everything is made of tiny particles[cite: 57]. However, in solid materials, these particles cannot move much, unlike in gases where they move around freely[cite: 57].
7
Assertion (A): Mixtures are combinations of materials that can be separated physically.
Reason (R): Compounds consist of two or more elements bonded together.
Reason (R): Compounds consist of two or more elements bonded together.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements correctly classify different types of materials, but the definition of compounds does not explain why mixtures can be physically separated[cite: 59].
8
Assertion (A): Only highly polished surfaces like mirrors can reflect light.
Reason (R): Rough surfaces and celestial bodies like the Moon also reflect light.
Reason (R): Rough surfaces and celestial bodies like the Moon also reflect light.
Answer: (d)
A is false, but R is true. Reflection is not limited to polished mirrors; rough surfaces reflect light as well, and this is also how we are able to see the Moon[cite: 64].
9
Assertion (A): Calendars determining our routines on Earth are linked to the motions of objects far beyond our planet.
Reason (R): Humans created early calendars by combining careful observations of sunrises, sunsets, and lunar cycles.
Reason (R): Humans created early calendars by combining careful observations of sunrises, sunsets, and lunar cycles.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Because early humans observed the periodic cycles of the Sun and the Moon's phases, they were able to formulate the first calendars that govern our routines[cite: 66, 67, 68].
10
Assertion (A): Human activities can disrupt climate patterns and have dangerous consequences for the Earth.
Reason (R): Human activities cause small changes in the temperature of the Earth.
Reason (R): Human activities cause small changes in the temperature of the Earth.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. It is these small, human-induced changes in the Earth's temperature that lead to the disruption of larger climate patterns and subsequent dangerous consequences[cite: 79].
11
Assertion (A): When investigating why a puri puffs up, it is best to change multiple conditions at the same time to get faster results.
Reason (R): In scientific experiments, it is better to change only one thing at a time while keeping other conditions the same.
Reason (R): In scientific experiments, it is better to change only one thing at a time while keeping other conditions the same.
Answer: (d)
A is false, but R is true. Changing multiple things at once makes it impossible to know which change caused the result. A proper scientific investigation involves changing only one variable at a time while keeping the rest constant[cite: 106].
12
Assertion (A): Every living being depends on and responds to the air, water, sunlight, and other organisms around them.
Reason (R): The complex relationships between living organisms and their environments form ecosystems that support life.
Reason (R): The complex relationships between living organisms and their environments form ecosystems that support life.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The dependency and response of living beings to abiotic and biotic factors are exactly what create the complex environmental patterns known as ecosystems[cite: 73, 74].
13
Assertion (A): Corrective glasses help many people see clearly because of the bending of light.
Reason (R): Light rays bend when passing through lenses.
Reason (R): Light rays bend when passing through lenses.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The specific property of light bending as it passes through the lenses in corrective glasses is what adjusts the image and helps people see clearly[cite: 62, 63].
14
Assertion (A): You need a fancy laboratory to do simple scientific experiments.
Reason (R): Everyday phenomena in a kitchen, like frying a puri, can be used for systematic scientific investigation.
Reason (R): Everyday phenomena in a kitchen, like frying a puri, can be used for systematic scientific investigation.
Answer: (d)
A is false, but R is true. Science is everywhere, and you do not need a fancy lab to observe, ask questions, and perform systematic experiments; a simple kitchen is often enough[cite: 87, 88, 117].
15
Assertion (A): Sugar dissolving in tea to make it sweet is an example of understanding how particles combine or mix to form solutions.
Reason (R): Pure substances around us are classified as elements.
Reason (R): Pure substances around us are classified as elements.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements are scientifically accurate, but defining pure substances as elements does not explain the process of mixing solutions like sugar and tea[cite: 59, 60].
❓ Frequently Asked Questions
What is covered in CBSE Class 8 Science Chapter 1 Exploring the Investigative World of Science?
This chapter covers all key topics from Exploring the Investigative World of Science as per CBSE 2026-27 syllabus.
Is this Assertion & Reason useful for CBSE board exams?
Yes, designed for CBSE Class 8 board exam preparation covering the complete syllabus.
Are these CBSE Class 8 Science Assertion & Reason updated for 2026-27?
Yes, all content at eBookPublisher is updated as per the latest 2026-27 CBSE syllabus.
How many chapters are in CBSE Class 8 Science?
All chapters of CBSE Class 8 Science are covered at eBookPublisher with free Assertion & Reason for each chapter.
Can I study Exploring the Investigative World of Science online for free?
Yes, complete Assertion & Reason for Exploring the Investigative World of Science is available free at eBookPublisher. Study online directly — no download needed.
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