Question

Which of the following reactions give hydrogen gas? \[ \begin{aligned} \text{I. }&\text{Reaction of tin with steam} \text{II. }&\text{Passage of steam over hot coke} \text{III. }&\text{Passage of air over hot coke} \end{aligned} \] The correct answer is

• A. I, III only
• B. I, II only
• C. I, II, III
• D. II only

Hint:

Remember the gases formed: \[ \boxed{ \text{Steam + hot coke} \rightarrow \text{Water gas }(CO+H_2) } \] \[ \boxed{ \text{Air + hot coke} \rightarrow \text{Producer gas }(CO+N_2) } \]

Answer 1

The Correct Option is B

Step 1: Check Reaction I. Tin reacts with steam to produce tin oxide and hydrogen. \[ \mathrm{Sn+2H_2O(g)\rightarrow SnO_2+2H_2}. \] Hence, hydrogen is produced.

Step 2: Check Reaction II. Steam passed over hot coke gives water gas. \[ \mathrm{C+H_2O(g)\rightarrow CO+H_2}. \] Hence, hydrogen is produced.

Step 3: Check Reaction III. Passing air over hot coke produces producer gas. \[ \mathrm{2C+O_2+4N_2\rightarrow2CO+4N_2}. \] No hydrogen gas is formed. Therefore, only reactions I and II produce hydrogen. Hence, \[ \boxed{(B)} \] is the correct answer.