When hydrogen burns in oxygen, water is formed and when water is electrolysed, then hydrogen and oxygen are produced. What type of reaction takes place :

(a) in the first case ?

(b) in the second case ?

Q.

When hydrogen in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical changes involved in the two cases.

Q. When hydrogen burns in oxygen, water is formed. The type of chemical change involved is:

Q. (a) When sodium is burnt in chlorine, sodium chloride is formed, and when molten sodium chloride is electrolysed, then sodium and chlorine are formed. What type of reaction takes place:
(i) in the first case?
(ii) in the second case?
(b) When hydrogen is passed over heated copper oxide, copper and steam are formed. Write a balanced chemical equation for this reaction. State which of the chemicals is oxidised and which one is reduced?
​(c) What would you observe when zinc is added to a solution of iron sulphate? Write the chemical equation of the reaction which takes place. Why does this reaction occur?

Q.

Name the type of chemical reactions involved in the cases given below:​

1. Burning of hydrogen to form water​

2. Passage of electricity through water that gives out hydrogen and oxygen ​

Q. When water is electrolysed, hydrogen and oxygen gases are produced. If $1.008g$ of $H_2$ is liberated at cathode, what mass of $O_2$ is formed at the anode?