In which of the following reactions, $\mathrm{H}_2$ is liberated? i. $\mathrm{Al}(\mathrm{s})+\mathrm{H} \mathrm{Cl}(\mathrm{aq}) \rightarrow$ ii. $\mathrm{A} /(\mathrm{s})+\mathrm{NaOH}(\mathrm{aq}) \rightarrow$ iii. $\mathrm{B}_2 \mathrm{H}_6(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(l) \rightarrow$ iv. $\mathrm{F}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(l) \rightarrow$

• A

  i, ii, iii, iv
• B

  i, ii, iv
• Correct answer
  C

  i, ii, iii
• D

  ii, iii, iv

Hence, the correct answer is option: 'C'.