A solid cube just gets completely immersed in water when a 0.2 kg mass is placed on it. If the mass is removed, the cube is 2 cm above the water level. What is the length of each side of the cube?

A hollow sphere of radius R, a hollow cube of side R and a thin circular plate of radius R, made up of the same material, are all heated to 20° C above room temperature. When left to cool in the room, which of them will reach the room temperature first?

If a potato is placed on a pure paper plate which is white and unprinted and put in a microwave oven, the potato heats up but the paper plate does not. This is because

Consider the following statements
1.Light of longer wavelength is scattered much more than the light of shorter wavelength.
2.The speed of visible light in water is 0.95 times the speed in vacuum.
3.Radio waves are produced by rapidly oscillating electrical currents.
4.To detect the overspeeding vehicles, police use the Doppler effect of reflected short radio waves.
Which of these statements are correct?

What is the principle by which a cooling system (Radiator) in a motor car works?

Which one of the following reflects back more sunlight as compared to other three?

Indiscriminate disposal of used fluorescent electric lamps causes mercury pollution in the environment. Why is mercury uses in the manufacture of these lamps?

Assertion (A): With the increase of temperature, the viscosity of glycerine increases.
Reason (R): Rise of temperature increases kinetic energy of molecules.
Codes

Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece.
Reason (R) : The density of copper is more than that of glass.
Codes

Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water.
Reason (R): A light coming from the stick undergoes scattering from water molecules giving the stick a short and bent appearance.
Codes