# NCERT Science Major Test Model Paper Class 7 2020 Questions and Answers Part 1

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## Section-A: Physics

1. A cake has to be baked at a temperature of . What is this temperature on the Celsius scale?

(1)

(2)

(3)

(4)

Ans: Option (3)

2. According to new convention, the colour coding for live wire is

(1) Red

(2) Brown

(3) Black

(4) Light blue

Ans: Option (2)

3. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear view mirror the image of truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be

(1) 1 m/s

(2) 2 m/s

(3) 4 m/s

(4) 8 m/s

Ans: Option (2)

4. Assertion: It is quite easy to cut vegetables with blunt knife.

Reason: Pressure is inversely proportional to area, i.e.. less area more pressure and vice-versa.

(1) Both assertion and reason are correct.

(2) Both assertion and reason are incorrect.

(3) Assertion is correct, and reason is incorrect.

(4) Assertion is incorrect, and reason is correct.

Ans: Option (1)

5. Give any two example of luminous and non-luminous body each.

Ans: Luminous body - Star, bulb etc.

Non-luminous body - Moon, chain etc.

6. How atmospheric pressure changes with altitude?

Ans: The force put on a given area by the weight of the air above it is called atmospheric pressure. Air pressure decreases with altitude.

7. (i) Write any one use of maximum of minimum thermometer?

(ii) What is a temperature of 86 °F on the Celsius scale?

Ans: (i)

(a) Maximum thermometer is used to measure highest temperature reached in a day.

(b) Minimum thermometer is used to measure lowest temperature attained in a day.

(ii)

8. (i) Why a concave mirror is also known as converging mirror.

(ii) An incident ray strikes a plane mirror at an angle of 15° with the mirror. The angle between incident ray and reflected ray is

Ans: (i) Concave mirror is also called ‘converging mirror’ because the parallel beam of light after reflection, converge at a single point.

(ii) Incident angle

Reflected angle

Also, Angle between incident ray and reflected ray is

9. (i) Write any three qualities of good earthing system.

(ii) Why in . three pin plug, the earth pin is made longer and thicker than other pins?

Ans:

(i) The qualities of a good earthing system are:

• Must be of low electrical resistance.
• Must be of good corrosion resistance.
• Must be able to dissipate high fault currents repeatedly and rapidly.

(ii) In a ‘three pin plug’ the earth pin is made longer and thicker than other pins for safety purpose to reduce the risk of shock. If the area of contact is more, resistance will be less, which provides easy flow of current to the earth. Such that any leakage current appearing on metal body of the equipment must be discharged safely to the ground.