set 4 MCQ Questions & Answers Detailed Explanation

Question : 1

Consider the following statements about ultrasonic waves.

1. They can destroy insects.
2. They can clean clothes by removing dust.
3. They can be used to treat diseases.
4. They can control automatic doors.

a) 3 and 4 are correct

b) 1, 2 and 3 are correct

c) 1 and 2 are correct

d) All are correct

Question : 2

Consider the following statements.

1. The sky appears blue because of less scattering.
2. The main cause of seven colours of the rainbow is scattering of light.
3. At the time of Sunrise, the Sun appears red, due to scattering of light.

a) Only 2 is true

b) 1 and 3 are true

c) Only 1 is true

d) 2 and 3 are true

Question : 3

Consider the following statements.

1. If a person looks at a coin which is in a bucket of water, the coin will appear to be closer than it really is.
2. If a person underwater looks at a coin above the water surface, the coin will appear to be at a higher level than it really is.

a) Only 2

b) Only 1

c) 1 and 2

d) Neither 1 nor 2

Question : 4

Which one of the following statement is not true for a person suffering from hypermetropia?

a) The image of the close objects is focused behind the retina

b) The focal length of the lens is large

c) The person can see far objects distinctly

d) A concave lens is used to correct this defect

Question : 5

Which one of the following changes occurs when salt is added into the water?

a) Boiling point is decreased and freezing point is increased

b) Both boiling point and freezing point are decreased

c) Boiling point is increased and freezing point is decreased

d) Both boiling point and freezing point are increased

Question : 6

A bimetallic strip consists of brass and iron. When it is heated it bends into an arc with brass on the convex and iron on the concave side of the arc. This happens because

a) it is easier to bend an iron strip than a brass strip of the same size

b) brass has a higher specific heat capacity than iron

c) density of brass is more than that of iron

d) brass has a higher coefficient of linear expansion than iron