light, heat, thermodynamics, wave motion, sound, optics & oscillations - Category wise Question and Answer Practice Test with Solutions

Question : 16 [UPPCS (Mains) 2004]

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 : 17 [PSC (Pre) 2014]

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 : 18 [IAS (Pre) 1999]

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 : 19 [CDS]

Assertion (A):
Steam is more harmful for human body than the boiling water in case of burn.
Reason (R) :
Boiling water contains more heat than steam.

a) Both A and R are true, but R is not the correct explanation of A

b) Both A and R are true and R is the correct explanation of A

c) A is true, but R is false

d) A is false, but R is true

Question : 20 [PSC (Pre) 2019]

An astronaut sees the colour of the sky as

a) Black

b) White

c) Blue

d) Red