Some sugar solution is taken in a test-tube and a little of substance X in powder form is added to it. The mouth of test-tube is closed with a cork and allowed to stand for some time. On opening the cork, a characteristic smell of substance Y is obtained and a gas Z is also observed to be formed. The gas Z extinguishes a burning matchstick. (a) What could be (i) X, (ii) Y, and (iii) Z? (b) What is the process of converting sugar into substance Y by the action of X known as? (c) What type of respiration is exhibited by X in the above process?