Class 10 Science MCQ – Electricity, Light & Environment

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Practice Class 10 Science MCQ Questions with Answers based on NCERT concepts. Revise electric potential difference, concave mirrors, greenhouse gases, plane mirrors and ozone layer depletion with clear exam-focused explanations.

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Chapter Information

• Subject: Science
• Class: 10
• Question Type: Multiple Choice Questions (MCQs)
• Difficulty Level: Easy to Moderate
• Based On: NCERT Class 10 Science Concepts
• Topics Covered: Electricity, Light and Environment

Introduction

This Class 10 Science MCQ practice set covers important concepts from electricity, light and environmental science. These questions are designed to help students revise important concepts and prepare effectively for school examinations and board-level practice.

What You Will Learn

✔ Electric potential difference and its SI unit
✔ Uses of concave mirrors
✔ Greenhouse gases
✔ Focal length of a plane mirror
✔ Ozone layer depletion and CFCs

Why This Topic Is Important

These concepts are important for understanding fundamental ideas in Class 10 Science. Regular MCQ practice can help students improve conceptual clarity, recall important facts, and answer objective questions more confidently.

Q1. Which mirror is used by dentists to see large images of teeth?

A) $$\text{Plane mirror}$$

B) $$\text{Convex mirror}$$

C) $$\text{Bifocal mirror}$$

D) $$\text{Concave mirror}$$

Answer:

$$\text{Concave mirror}$$

Concept / Exam Explanation:

A concave mirror can produce a magnified and upright image when the object is placed between the pole and focus. This property makes it useful for dentists to examine teeth.

Exam Tip:

Important uses of concave mirrors include:

✔ Dentist’s mirror
✔ Shaving mirror
✔ Reflectors in torches and headlights

Dentists use a concave mirror to see a larger image of teeth.

Why concave mirror is used:

• It forms a magnified image when the object is placed close to the mirror
• Helps dentists examine teeth clearly

Properties of concave mirrors:

• Can produce enlarged images
• Reflect light inward toward a focus point

Other uses:

• Shaving mirrors
• Headlights of vehicles
• Solar furnaces

Example:
Dentists use concave mirrors to check cavities and small details in teeth.

Q2. The SI unit of electric potential difference is:

A) $$\text{Watt}$$

B) $$\text{Joule}$$

C) $$\text{Volt}$$

D) $$\text{Ampere}$$

Answer:

$$\text{Volt}$$

Concept / Exam Explanation:

Electric potential difference is the work done per unit electric charge in moving a charge between two points.

Its SI unit is:

$$\text{Volt (V)}$$

The relationship is:

$$V=\frac{W}{Q}$$

where $$W$$ represents work done and $$Q$$ represents electric charge.

Exam Tip:

Remember:

$$\text{Potential Difference} \rightarrow \text{Volt}$$

Electric potential difference is measured in volts (V).

Meaning of potential difference:
It is the work done to move a unit charge from one point to another in an electric circuit.

SI Unit:
Volt (V)

Named after:
Alessandro Volta, a famous scientist.

Measuring device:
A voltmeter is used to measure potential difference.

Example:
A household battery may have a potential difference of 1.5 volts.

Q3. Which of the following is a greenhouse gas?

A) $$\text{Nitrogen}$$

B) $$\text{Carbon dioxide}$$

C) $$\text{Argon}$$

D) $$\text{Oxygen}$$

Answer:

$$\text{Carbon dioxide (CO}_2\text{)}$$

Concept / Exam Explanation:

Carbon dioxide is an important greenhouse gas. Greenhouse gases absorb and retain some of the heat in Earth’s atmosphere, contributing to the greenhouse effect.

Other greenhouse gases include methane, nitrous oxide and water vapour.

Exam Tip:

Among the given options:

$$\boxed{\text{Carbon dioxide}}$$

is the correct answer.

Carbon dioxide (CO₂) is one of the main greenhouse gases present in the atmosphere.

How greenhouse gases work:
They trap heat from the Sun and warm the Earth’s atmosphere.

Sources of carbon dioxide:

• Burning fuels
• Vehicles
• Factories
• Deforestation

Effects of excess greenhouse gases:

• Global warming
• Climate change
• Rising temperatures

Importance:
A small amount is necessary to maintain Earth’s temperature, but excess amounts are harmful.

Q4. What is the focal length of a plane mirror?

A) $$\infty$$

B) $$25,cm$$

C) $$0$$

D) $$-25,cm$$

Answer:

$$\infty$$

Concept / Exam Explanation:

A plane mirror can be considered to have an infinite radius of curvature. Since:

$$f=\frac{R}{2}$$

when:

$$R=\infty$$

the focal length is also:

$$f=\infty$$

Exam Tip:

Remember:

$$\boxed{\text{Plane mirror} \rightarrow \text{Infinite focal length}}$$

The focal length of a plane mirror is considered to be infinity.

Reason:
A plane mirror has a flat surface, so reflected rays do not meet at a single point.

Understanding focal length:
Focal length is the distance between the mirror and its focus point.

In plane mirrors:

• Radius of curvature is infinite
• Therefore focal length is also infinite

Image properties:

• Virtual and erect
• Same size as the object

Q5. Factors responsible for the depletion of the ozone layer are:

A) $$\text{CFCs}$$

B) $$\text{Hydrogen}$$

C) $$\text{Methane}$$

D) $$\text{Carbon monoxide}$$

Answer:

$$\text{CFCs (Chlorofluorocarbons)}$$

Concept / Exam Explanation:

Chlorofluorocarbons, commonly known as CFCs, are important ozone-depleting substances. Their breakdown in the upper atmosphere releases chlorine-containing compounds that participate in reactions that destroy ozone.

The ozone layer is important because it absorbs a significant amount of harmful ultraviolet radiation from the Sun.

Exam Tip:

Remember: $$\boxed{\text{Ozone depletion} \rightarrow \text{CFCs}}$$

Chlorofluorocarbons (CFCs) are mainly responsible for the depletion of the ozone layer.

What is the ozone layer?
It is a protective layer in the atmosphere that absorbs harmful ultraviolet (UV) rays from the Sun.

Sources of CFCs:

• Refrigerators
• Air conditioners
• Aerosol sprays

Effects of ozone depletion:

• Increased UV radiation reaching Earth
• Skin diseases and eye damage
• Harm to plants and animals

Prevention:
Reducing the use of CFC-based products helps protect the ozone layer.

Important Formulas & Concepts

1. Electric Potential Difference

$$V=\frac{W}{Q}$$

2. SI Unit of Potential Difference

$$\text{Volt (V)}$$

3. Plane Mirror

$$R=\infty$$

Therefore:

$$f=\infty$$

4. Concave Mirror

A concave mirror can produce a magnified, upright image when the object is placed between the pole and focus.

5. Ozone Layer

The ozone layer absorbs a significant portion of harmful UV radiation from the Sun.

Related Practice Questions

1. What is the SI unit of electric current?
2. Which mirror is used in vehicle rear-view mirrors?
3. Name two greenhouse gases.
4. What type of image is generally formed by a plane mirror?
5. What are CFCs and why are they harmful to the ozone layer?

Mini Quiz Challenge

1. The SI unit of electric current is:

A) Volt
B) Ampere
C) Watt
D) Joule

Answer: $$\text{Ampere}$$

2. Which mirror is commonly used as a rear-view mirror?

A) Plane mirror
B) Concave mirror
C) Convex mirror
D) Bifocal mirror

Answer: $$\text{Convex mirror}$$

3. Which substance is strongly associated with ozone depletion?

A) CFCs
B) Oxygen
C) Nitrogen
D) Hydrogen

Answer: $$\text{CFCs}$$

Exam Tips

✔ Learn SI units together with their corresponding physical quantities.
✔ Remember the practical applications of concave and convex mirrors.
✔ Do not confuse greenhouse gases with ozone-depleting substances.
✔ Remember that the focal length of a plane mirror is considered infinite.
✔ Learn the role of CFCs in ozone depletion.

Quick Revision Notes

✔ Electric potential difference → Volt
✔ Dentist’s mirror → Concave mirror
✔ Greenhouse gas → Carbon dioxide
✔ Plane mirror focal length → $$\infty$$
✔ Ozone depletion → CFCs
✔ Plane mirror → Image is virtual, upright and same size as the object

Common Mistakes Students Make

❌ Confusing Volt with Watt or Joule.
❌ Choosing a convex mirror instead of a concave mirror for a dentist’s mirror.
❌ Assuming every atmospheric gas is a greenhouse gas.
❌ Thinking that a plane mirror has zero focal length.
❌ Confusing greenhouse gases with substances responsible for ozone depletion.

Key Takeaways

• The SI unit of electric potential difference is Volt.
• A concave mirror can produce a magnified upright image for a nearby object.
• Carbon dioxide is a greenhouse gas.
• The focal length of a plane mirror is considered infinite.
• CFCs are major ozone-depleting substances.

FAQs

1. What is the SI unit of electric potential difference?

The SI unit is Volt (V).

2. Which mirror is used by dentists?

A concave mirror is used because it can provide a magnified upright image of a nearby tooth.

3. Is carbon dioxide a greenhouse gas?

Yes. Carbon dioxide (CO₂) is an important greenhouse gas.

4. What is the focal length of a plane mirror?

The focal length of a plane mirror is considered:

$$\infty$$

5. What causes ozone layer depletion?

CFCs (Chlorofluorocarbons) are major substances responsible for ozone depletion.

NCERT Reference

This practice set is based on concepts covered in the NCERT Class 10 Science curriculum, particularly topics related to Electricity, Light – Reflection and Refraction, and Our Environment.

The questions, explanations, exam tips, revision notes and supporting content above are originally written for educational practice and are not copied from NCERT textbook passages.

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