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Practice Class 9th Science MCQ Questions with Answers based on NCERT concepts. Revise electron discovery, SI unit of density, uniform acceleration, evaporation and functions of parenchyma tissue with clear explanations and exam-focused revision notes.
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Chapter Information
Subject: Science
Class: 9
Topics: Structure of the Atom, Matter in Our Surroundings, Motion, and Tissues
Question Type: Multiple Choice Questions (MCQs)
Difficulty Level: Easy to Moderate
Based On: NCERT Concepts
Introduction
Class 9 Science introduces students to important concepts from Physics, Chemistry and Biology. Understanding atomic structure, physical changes of matter, motion and plant tissues creates a strong foundation for higher-level Science.
This MCQ practice set covers five important concepts related to the discovery of the electron, density, uniform acceleration, evaporation and the function of parenchyma tissue.
What You Will Learn
✔ Discovery of the electron
✔ SI unit of density
✔ Meaning of uniform acceleration
✔ Evaporation of liquids
✔ Main function of parenchyma tissue
Why This Topic Is Important?
These concepts are frequently used in basic Science questions and help students understand important principles in Physics, Chemistry and Biology. A clear understanding of these fundamentals also makes it easier to solve numerical and conceptual questions in higher classes.
Exam Relevance
These questions are useful for:
✔ School Tests
✔ Unit Tests
✔ Half-Yearly Exams
✔ Annual Exams
✔ Science Quizzes
✔ Class 9 Examination Revision
Q1. Which process involves change of liquid into gas at any temperature?
A) Evaporation
B) Boiling
C) Sublimation
D) Condensation
Answer
Evaporation
Concept
Evaporation is the change of a liquid into vapour from its surface and can occur at temperatures below its boiling point.
Explanation
Evaporation is a surface phenomenon. It can occur at different temperatures, provided suitable conditions exist.
Boiling is different because it occurs throughout the liquid at its boiling point under a given pressure.
Exam Focus
Liquid → Gas at the surface and at temperatures below boiling point → Evaporation
Evaporation is a process in which a liquid changes into vapor at any temperature, without reaching its boiling point. It happens only at the surface of the liquid and occurs slowly.
How it works:
Some particles of the liquid gain enough energy to escape from the surface and become gas.
Factors affecting evaporation:
- Higher temperature increases the rate
- Larger surface area speeds it up
- Faster air movement (wind) increases evaporation
- Lower humidity helps evaporation occur faster
Example: Sweat cools our body because it evaporates and takes heat away.
Q2. SI unit of density is:
A) $$kg/m$$
B) $$g/cm^3$$
C) $$kg/m^3$$
D) $$m^3/kg$$
Answer
$$kg/m^3$$
Concept
Density represents the mass contained in a unit volume of a substance.
Formula
$$\text{Density}=\frac{\text{Mass}}{\text{Volume}}$$
Explanation
The SI unit of mass is kilogram (kg) and the SI unit of volume is cubic metre ($$m^3$$).
Therefore:
$$\text{SI unit of density}=\frac{kg}{m^3}$$
Exam FocusSI unit of density → $$kg/m^3$$
Density describes how much mass is present in a given volume of a substance.
Formula:
Density = Mass ÷ Volume
Simple idea:
If two objects are the same size but one is heavier, that one has greater density.
Why kg/m³?
Because mass is measured in kilograms and volume in cubic meters in the SI system.
Examples:
- Iron sinks in water because it has higher density
- Oil floats on water because it has lower density
Q3. Who discovered the electron?
A) Rutherford
B) Bohr
C) J.J. Thomson
D) Dalton
Answer
J.J. Thomson
Concept
The electron was discovered through experiments involving cathode rays.
Explanation
J.J. Thomson conducted experiments with cathode ray tubes and showed that cathode rays consisted of negatively charged particles. These particles were later known as electrons.
Exam Focus
Remember:
Electron → J.J. Thomson
The electron was discovered by J.J. Thomson in 1897 through experiments using cathode rays.
What he did:
He passed electricity through a vacuum tube and observed rays coming from the cathode.
What he found:
- These rays were made of tiny negatively charged particles
- These particles were later named electrons
Importance:
This discovery proved that atoms are made of smaller particles and are not indivisible.
Q4. Uniform acceleration means:
A) Constant change in velocity
B) Increasing velocity
C) Decreasing velocity
D) Zero velocity
Answer
Constant change in velocity
Concept
Uniform acceleration means that the velocity of an object changes by an equal amount in equal intervals of time.
Explanation
Acceleration describes the rate at which velocity changes with time.
For uniform acceleration, the change in velocity remains constant for equal time intervals.
For example, if the velocity changes by the same amount every second, the object has uniform acceleration.
Formula
$$a=\frac{\text{Change in velocity}}{\text{Time}}$$
or
$$a=\frac{v-u}{t}$$
where:
$$u=\text{Initial velocity}$$
$$v=\text{Final velocity}$$
$$t=\text{Time}$$
Exam Focus
Uniform acceleration → Equal change in velocity in equal time intervals
Uniform acceleration occurs when the velocity of an object changes by equal amounts in equal intervals of time.
In simple terms:
The speed increases or decreases at a steady and constant rate.
Formula:
Acceleration = Change in velocity ÷ Time
Graph:
A velocity-time graph shows a straight line in this case.
Examples:
- An object falling freely under gravity
- A vehicle increasing speed at a constant rate
Q5. Parenchyma tissue mainly functions in:
A) Protection
B) Storage
C) Support
D) Transport
Answer
Storage
Concept
Parenchyma is a simple permanent plant tissue that commonly performs functions such as storage.
Explanation
Parenchyma cells are generally living and have relatively thin cell walls. In many parts of plants, they store food and other substances.
Some specialised forms of parenchyma can also perform other functions. For example, chlorophyll-containing parenchyma can participate in photosynthesis.
Exam Focus
Parenchyma → Mainly associated with storage
Parenchyma is a basic plant tissue made up of living cells. It is found in soft parts of plants.
Main functions:
- Storage of food and water
- Photosynthesis (if chlorophyll is present)
- Exchange of gases (if air spaces are present)
Structure:
- Thin cell walls
- Cells are loosely packed with spaces between them
Examples:
- Storage of starch in potatoes
- Photosynthesis in leaves
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