What do you understand by fuel efficiency?

Write True/False against the following statements and also correct the false statement.

(a) A physical process in which a substance reacts with oxygen to give off heat is called combustion.

(b) Water is the best extinguisher for fires involving electrical equipment.

(c) Alcohol, CNG and LPG are inflammable substances.

(d) Increased concentration of nitrogen in air is believed to cause global warming.

(e) Greater the calorific value, better is the fuel.

(f) Middle zone is the hottest zone of a flame.

(g) The substances which vaporize during burning, give flame.

Cracker on ignition produces sound. Why?

You are provided with three watch glasses containing milk, petrol and mustard oil, respectively. Suppose you bring a burning candle near these materials one by one, which material(s) will catch fire instantly and why?

Manu was heating oil to fry potato chips. The cooking oil all of a sudden caught fire; he poured water to extinguish the fire. Do you think this action was suitable? If yes, why? If not, why not? In such a condition what should Manu have done?