Units, Dimensions and Measurement — JEE physics STD 12 Science — Question

Assertion : An object can have constant speed but variable velocity.
Reason : Speed is a scalar but velocity is a vector quantity.

Assertion : For a floating body to be in stable equilibrium, its centre of buoyancy must be located above the centre of gravity.
Reason : The torque produced by the weight of the body and the upthrust will restore body back to its normal position, after the body is disturbed.

Assertion : The change in air pressure effect the speed of sound.
Reason : The speed of sound in a gas is proportional to square root of pressure.

Assertion : A reference frame attached to earth is an inertial frame of reference.
Reason : The reference frame which has zero acceleration is called a non inertial frame of reference.

Assertion : If a plane glass slab is placed on the letters of different colours all the letters appear to be raised up to the same height.
Reason : Different colours have different wavelengths.

Assertion : The velocity of fall of a man jumping with a parachute first increases and then becomes constant.
Reason : The constant velocity of fall of man is called terminal velocity.

Assertion : The stretching of a coil is determined by its shear modulus.
Reason : Shear modulus change only shape of a body keeping its dimensions unchanged.

Assertion : Water kept in an open vessel will quickly evaporate on the surface of the moon.
Reason : The temperature at the surface of the moon is much higher than boiling point of the water.

Assertion : When a gas is allowed to expand, work done by gas is positive.
Reason : Force due to gaseous pressure and displacement (of piston) are in the same direction.