Hydrogen Ques 9
9. Which one of the following pairs of substances on reaction will not evolve $\mathrm{H}_2$ gas?
(a) Iron and $\mathrm{H}_2 \mathrm{SO}_4$ (aqueous)
(b) Iron and steam
(c) Copper and $\mathrm{HCl}$ (aqueous)
(d) Sodium and ethyl alcohol
Show Answer
Answer:
Correct Answer: 9.(c)
Solution: (c) $\mathrm{Fe}+$ dil. $\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{FeSO}_4+\mathrm{H}_2 \uparrow$
$3 \mathrm{Fe}+4 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Fe}_3 \mathrm{O}_4+4 \mathrm{H}_2 \uparrow$
$\mathrm{Cu}+$ dil. $\mathrm{HCl} \rightarrow$ No reaction
Copper does not evolve $\mathrm{H}_2$ from acid as it is below hydrogen in electrochemical series.
$ 2 \mathrm{Na}+\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH} \rightarrow 2 \mathrm{C}_2 \mathrm{H}_5 \mathrm{ONa}+\mathrm{H}_2 \uparrow $
BETA
