Physics

1.Supersonic plane fly with the speed

less than the speed of sound of sound greater than the speed of sound of light

2.Mach number is used in connection with the speed of

sound aircraft spacecraft ships

3.On a stationary sail boat, air is blown from a fan attached to the boat. The boat

moves in opposite direction in which the air is blown does not move moves in the same direction in which air blows spins around

4.Rainbow is due to

absorption of sunlight in minute water droplets diffusion of sunlight through water droplets ionisation of water deposits refraction and reflection of sunlight by water droplets

5.Stars which appear single to the naked eye but are double when seen through a telescope are

novas and supernovas binaries asteroids quasars

Physics

1.Radiocarbon is produced in the atmosphere as a result of

collision between fast neutrons and nitrogen nuclei present in the atmosphere

action of ultraviolet light from the sun on atmospheric oxygen 

action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere 

lightning discharge in atmosphere

2.It is easier to roll a stone up a sloping road than to lift it vertical upwards because

work done in rolling is more than in lifting work done in lifting the stone is equal to rolling it work done in both is same but the rate of doing work is less in rolling work done in rolling a stone is less than in lifting it

3.The absorption of ink by blotting paper involves

viscosity of ink capillary action phenomenon diffusion of ink through the blotting siphon action

4.Siphon will fail to work if

the densities of the liquid in the two vessels are equal the level of the liquid in the two vessels are at the same height both its limbs are of unequal length the temperature of the liquids in the two vessels are the same

5.Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to

the heating effect of current alone hysteresis loss alone both the heating effect of current and hysteresis loss intense sunlight at noon