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Practice Class 9 Science MCQ questions based on NCERT concepts covering boiling, acceleration, neutron charge, power, and phloem with clear exam-focused explanations and revision notes.
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Chapter Information
Subject: Science
Class: 9
Question Type: Multiple Choice Questions (MCQs)
Difficulty Level: Moderate
Based On: NCERT-aligned concepts
Introduction
This Class 9 Science MCQ practice set covers important concepts from Matter, Motion, Force and Laws of Motion, Work and Energy, and Tissues. The questions are designed to strengthen conceptual understanding and help students prepare for school examinations and regular revision.
What You Will Learn
✔ Boiling as a bulk phenomenon
✔ Different types of acceleration
✔ Charge of a neutron
✔ SI unit of power
✔ Function of phloem in plants
Why This Topic Is Important
These concepts are frequently used in Class 9 Science examinations. Understanding the basic scientific principles behind each answer makes it easier to solve both direct and concept-based questions.
Exam Relevance
These MCQs are useful for:
✔ NCERT-based examinations
✔ School tests
✔ Unit tests
✔ Half-yearly examinations
✔ Annual examinations
✔ Science revision
Q1. Boiling is a:
A) Surface phenomenon
B) Chemical change
C) Reversible change
D) Bulk phenomenon
Answer:
Bulk phenomenon
Concept / Exam Explanation
Boiling occurs throughout the bulk of a liquid when the liquid reaches its boiling point. Vapour bubbles form within the liquid and rise to the surface.
Therefore, boiling is classified as a bulk phenomenon.
Boiling is also a physical and reversible change, but in this question the specific classification being asked is bulk phenomenon.
Exam Tip
Remember the difference:
Evaporation → Surface phenomenon
Boiling → Bulk phenomenon
Boiling is the process in which a liquid changes into gas throughout the whole liquid, not just at the surface.
Key Points:
- It occurs at a fixed temperature called the boiling point
- Bubbles are formed inside the liquid
- Entire liquid takes part in the process
Difference from Evaporation:
- Boiling → happens in the whole liquid
- Evaporation → happens only at the surface
Example:
Water boiling at 100°C.
Q2. Unit of power:
A) Joule
B) Watt
C) Pascal
D) Newton
Answer:
Watt
Concept / Exam Explanation
Power measures the rate at which work is done:
$$P=\frac{W}{t}$$
The SI unit of power is watt (W).
One watt means one joule of work is done in one second:
$$1,W=1,J/s$$
Exam Tip
Remember these common units:
Work → Joule
Power → Watt
Force → Newton
Pressure → Pascal
Power tells us how fast work is done or energy is used.
Formula:
Power = Work ÷ Time
SI Unit: Watt (W)
Key Points:
- Higher power means faster work
- Lower power means slower work
Example:
Electric appliances like bulbs, fans, and heaters are rated in watts.
Q3. Neutron charge:
A) Variable
B) Positive
C) Neutral
D) Negative
Answer:
Neutral
Concept / Exam Explanation
A neutron has no net electric charge. It is electrically neutral.
For comparison:
- Proton → Positive charge
- Electron → Negative charge
- Neutron → No net charge
Exam Tip
A simple way to remember:
Proton = +
Electron = −
Neutron = 0
A neutron is a particle present in the nucleus of an atom.
Charge:
- Neutron has no charge (neutral)
Comparison:
- Proton → positive
- Electron → negative
Importance:
Neutrons help keep the nucleus stable.
Q4. Acceleration can be:
A) Positive
B) Negative
C) Zero
D) All of these
Answer:
All of these
Concept / Exam Explanation
Acceleration describes the rate of change of velocity with time:
$$a=\frac{v-u}{t}$$
Depending on the change in velocity, acceleration can be:
- Positive → velocity increases in the chosen positive direction.
- Negative → velocity decreases or changes in the opposite direction.
- Zero → velocity remains constant.
Therefore, acceleration can be positive, negative, or zero.
Exam Tip
Do not assume acceleration is always positive. Its sign depends on the change in velocity and the chosen direction.
Acceleration is the change in velocity over time.
Formula:
Acceleration = Change in velocity ÷ Time
Types:
- Positive → speed increases
- Negative → speed decreases (retardation)
- Zero → no change in speed
Example:
- Car speeding up → positive acceleration
- Car slowing down → negative acceleration
- Car moving at constant speed → zero acceleration
Q5. Phloem carries:
A) Water
B) Food
C) Oxygen
D) Minerals
Answer:
Food
Concept / Exam Explanation
Phloem is a vascular tissue that transports food, mainly sugars produced during photosynthesis, from leaves to other parts of the plant.
The movement of food through phloem can occur from the source to areas where food is needed or stored.
In contrast, xylem mainly transports water and minerals from the roots toward other parts of the plant.
Exam Tip
Remember:
Xylem → Water + minerals
Phloem → Food
Phloem is a plant tissue that transports food made in leaves to other parts of the plant.
Key Points:
- Carries food like glucose
- Transport can happen in both directions
Difference from Xylem:
- Phloem → transports food
- Xylem → transports water and minerals
Example:
Food prepared in leaves moves to roots and stems through phloem.
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