Light, Heat, Thermodynamics, Wave Motion, Sound, Optics & Oscillations - Category Wise Question And Answer Practice Test With Solutions

Question : 21

When the distance between the object and the plane mirror increases

a) the distance between the image and the plane mirror increases

b) the image remains same

c) the size of the image will become less than the size of the object

d) the distance between the image and the plane mirror decreases

Question : 22

When pressure on piece of ice is increases its melting point

a) increases

b) decreases

c) remains unchanged

d) first increases and then decreases

Question : 23 [IAS Prelim]

The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason ?

a) Since the surface of the lake is at the same temperature as the air, no heat is lost.

b) Ice is a bad conductor of heat.

c) The density of water is maximum at 4°C.

d) None of the statements (a), (b) and (c) given is correct.

Question : 24 [PCS (Mains) 2002]

A radar which detects the presence of an enemy aircraft uses

a) Sound waves

b) Radio waves

c) Light waves

d) Ultrasound waves

Question : 25 [UPPCS (Pre) 1998]

Cosmic rays

a) can be charged as well as uncharged

b) are uncharged particles

c) are charged particles

d) None of the above