Choose the correct statements regarding fuels: (i) Fuels liberate heat on burning (ii) CNG is less polluting than petrol and diesel (iii) CNG is a non-conventional source of energy (iv) Coal is formed from plant remains

The mode of heat transfer by the actual movement of molecules in liquids and gases is:

Match the gases in column A with their harmful effects in column B: (i) Carbon monoxide (ii) Oxides of nitrogen (iii) Carbon dioxide, matched with (a) causes acid rain (b) causes global warming (c) forms carboxy-haemoglobin.

A 150 m long train is moving with a constant velocity of 45 kilometre/hour. The time taken by this train to cross a bridge of length 850 m is:

Blood cell is a: