Class 9 Science MCQ | Mole Concept, Neuron, Pressure, Speed & Latent Heat

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Practice Class 9 Science MCQ Questions with Answers based on the latest NCERT syllabus. Learn about the mole concept, neuron function, SI unit of pressure, scalar quantities, and latent heat with original concept-based explanations, exam-focused notes, and NCERT-aligned solutions for CBSE and State Board students.

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Chapter Information

Subject: Science

Class: 9

Chapters Covered:

• Atoms and Molecules
• Tissues
• Force and Laws of Motion
• Motion
• Matter in Our Surroundings

Question Type: Multiple Choice Questions (MCQs)

Difficulty Level: Moderate

Based On: Latest NCERT Syllabus

Introduction

Class 9 Science introduces students to fundamental concepts in Physics, Chemistry, and Biology. Topics such as the mole concept, tissues, motion, pressure, and properties of matter help students develop scientific thinking and prepare them for higher-level studies. This practice set provides concept-based MCQs with original explanations to improve understanding and examination performance.

What You Will Learn

✔ Mole concept and Avogadro’s number

✔ Function of neurons

✔ SI unit of pressure

✔ Scalar and vector quantities

✔ Latent heat and change of state

Why This Topic Is Important?

These concepts are essential for building a strong foundation in Science. They frequently appear in CBSE, State Board, Olympiad, and scholarship examinations. Understanding them also helps students solve both objective and descriptive questions with confidence.

Exam Relevance

These questions are useful for:

✔ CBSE Exams

✔ State Board Exams

✔ School Tests

✔ Unit Tests

✔ Half-Yearly Exams

✔ Annual Exams

✔ Olympiad Preparation

✔ Scholarship Examinations

Q1. 1 mole equals:

A) $$\mathrm{6 \times 10^{22}}$$

B) $$\mathrm{10^{22}}$$

C) $$\mathrm{10^{23}}$$

D) $$\mathrm{6.022 \times 10^{23}}$$

Answer

$$\mathrm{6.022 \times 10^{23}}$$

Concept

One mole represents a fixed number of particles known as Avogadro’s number.

Explanation

One mole of any substance contains $$\mathrm{6.022 \times 10^{23}}$$ particles, which may be atoms, molecules, or ions depending on the substance. This number provides a bridge between the microscopic world of atoms and the measurable quantities used in laboratories.

Exam Focus

Remember:

1 Mole = $$\mathrm{6.022 \times 10^{23}}$$ particles (Avogadro’s Number).

Q2. Neuron function:

A) Digestion

B) Movement

C) Transmission

D) Storage

Answer

Transmission

Concept

A neuron is the basic structural and functional unit of the nervous system.

Explanation

Neurons receive and transmit nerve impulses between different parts of the body. They carry messages from sense organs to the brain and spinal cord and send responses back to muscles and glands, enabling coordination and control.

Exam Focus

Remember:

Neuron → Transmission of nerve impulses.

Q3. Unit of pressure:

A) Pascal

B) Watt

C) Joule

D) Newton

Answer

Pascal

Concept

Pressure is defined as the force acting per unit area.

Explanation

The SI unit of pressure is Pascal (Pa). One Pascal is the pressure exerted when a force of 1 Newton acts uniformly on an area of 1 square metre.

Useful Formula:

$$P=\frac{F}{A}$$

where:

• $$P$$ = Pressure
• $$F$$ = Force
• $$A$$ = Area

Exam Focus

Remember:

SI Unit of Pressure = Pascal (Pa)

Q4. Speed is:

A) None

B) Both

C) Vector

D) Scalar

Answer

Scalar

Concept

Physical quantities are classified as scalar or vector based on whether they have direction.

Explanation

Speed is a scalar quantity because it has only magnitude and no direction. In contrast, velocity is a vector quantity because it has both magnitude and direction.

Exam Focus

Remember:

• Speed → Scalar
• Velocity → Vector

Q5. Latent heat is:

A) Hidden heat

B) Visible heat

C) Heat energy

D) Light energy

Answer

Hidden heat

Concept

Latent heat is associated with a change of state without a change in temperature.

Explanation

Latent heat is the heat absorbed or released by a substance during a change of state, such as melting or boiling, while its temperature remains constant. Because this heat does not produce a temperature change, it is often called hidden heat.

Exam Focus

Remember:

Latent Heat → Heat absorbed or released during a change of state without changing temperature.

Important Formulas & Concepts

1. Avogadro’s Number

$$\mathrm{1\ Mole = 6.022 \times 10^{23}\ particles}$$

2. Pressure Formula

$$P=\frac{F}{A}$$

SI Unit:

Pascal (Pa)

3. Scalar and Vector Quantities

Scalar Quantities

• Speed
• Distance
• Mass
• Time

Vector Quantities

• Velocity
• Force
• Displacement
• Acceleration

4. Neuron

• Structural and functional unit of the nervous system.
• Transmits nerve impulses throughout the body.

5. Latent Heat

• Heat absorbed or released during a change of state.
• Temperature remains constant during the process.

Related Practice Questions

1. What is Avogadro’s number?
2. Differentiate between speed and velocity.
3. Define pressure and write its SI unit.
4. What is the function of a neuron?
5. Explain latent heat with one example.

Mini Quiz Challenge

True or False

1. One mole contains $$\mathrm{6.022 \times 10^{23}}$$ particles.
2. Neurons transmit nerve impulses.
3. Pascal is the SI unit of pressure.
4. Speed is a vector quantity.
5. Latent heat changes the temperature of a substance during a change of state.

Exam Tips

✔ Memorize important SI units.

✔ Learn the difference between scalar and vector quantities.

✔ Remember Avogadro’s number accurately.

✔ Understand the role of neurons in the nervous system.

✔ Revise the concept of latent heat with everyday examples.

Quick Revision Notes

✔ One mole contains $$\mathrm{6.022 \times 10^{23}}$$ particles.

✔ Neurons transmit nerve impulses.

✔ Pascal is the SI unit of pressure.

✔ Speed is a scalar quantity.

✔ Velocity is a vector quantity.

✔ Latent heat is absorbed or released without changing temperature.

Common Mistakes Students Make

❌ Confusing speed with velocity.

❌ Writing Newton instead of Pascal as the SI unit of pressure.

❌ Forgetting the exact value of Avogadro’s number.

❌ Assuming latent heat increases temperature.

❌ Thinking neurons perform digestion or storage functions.

Key Takeaways

• One mole contains **$$\mathrm{6.022 \times 10^{23}}$$ particles.
• Neurons are responsible for transmitting nerve impulses.
• Pressure is measured in Pascal (Pa).
• Speed is a scalar quantity, while velocity is a vector quantity.
• Latent heat is involved in changes of state without changing temperature.

FAQs

1. What is one mole?

One mole is the amount of substance containing **$$\mathrm{6.022 \times 10^{23}}$$ elementary particles, known as Avogadro’s number.

2. What is the main function of a neuron?

A neuron transmits nerve impulses between different parts of the body.

3. What is the SI unit of pressure?

The SI unit of pressure is Pascal (Pa).

4. Is speed a scalar or vector quantity?

Speed is a scalar quantity because it has magnitude only.

5. What is latent heat?

Latent heat is the heat absorbed or released during a change of state without any change in temperature.

NCERT Reference

Book: NCERT Science Class 9

Chapters Covered:

• Chapter 3 – Atoms and Molecules
• Chapter 6 – Tissues
• Chapter 9 – Force and Laws of Motion
• Chapter 8 – Motion
• Chapter 1 – Matter in Our Surroundings

Based On: Latest NCERT Curriculum (CBSE)

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