# NCERT Class 7 Science Model Paper 2 Questions and Answers Part 1

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## Section – a: Physics

1. The atmospheric pressure is nearly

(1) 76 mm of Hg

(2) 760 mm of Hg

(3) 760 cm of Hg

(4) 760 m of Hg

Ans: Option (2)

2. If an object moving along a straight line, keeps changing its speed then,

(1) The motion is said to be a uniform motion.

(2) The motion is said to be a non-uniform motion.

(3) The object is said to be stationary.

(4) The motion is said to be a fast motion.

Ans: Option (2)

3. Which among the following is an example of conductor?

(1) Graphite

(2) Porcelain

(3) Pure water

(4) Wood

Ans: Option (1)

4. Assertion: Windstorms or other high winds sometimes blow roofs from houses.

Reason: Wind speed of a fluid increase, the pressure exerted by the fluid decreases.

(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. Write CGS and SI unit of velocity.

Ans: CGS unit of velocity: cm/sec

SI unit of velocity: m/s

6. What will be the order in which the bulbs A, B and C will glow when the switch is moved to the ‘ON’ position?

Ans: Bulbs will glow simultaneously. When the switch is moved to the ‘ON’ position, then all the bulbs will glow at once. This is because they all are connected to the same battery and switch.

7. Explain open and closed circuit with neat diagram.

Ans: (i) Open electric circuit: An electric circuit in which normal path of current has been interrupted.

(ii) Closed circuit: An electric circuit that provides uninterrupted, endless path for the flow of current.

8. Differentiate between regular and diffuse reflection (any three)

Ans: Regular and diffuse reflection

 Regular reflection (specular reflection) : Diffuse reflection (irregular reflection) (i) If a parallel beam of light is incident on a Smooth plane mirror, This reflection is called ‘regular reflection’ . If a parallel beam of light is incident on a rough surface or mirror, such a reflection is Called ‘diffuse reflection’ . (ii) The light rays get reflected at same angles of reflection. That is why, the rays of reflected beam remains parallel to each other. The light rays get reflected at many different angles. That is why, the rays of reflected beam become nonparallel to each other. (iii)Smooth Surface Rough Surface

9. State the properties of the image formed by a plane mirror.

Ans: The properties of image formed by plane mirrors are:

(1) The image is virtual and erect.

(2) The distance of image from mirror is equal to distance of object from mirror.

(3) The size of image is exactly equal to the size of object.

(4) The image is laterally inverted.