Question

In which of the following cases a chemical reaction is possible ?

• A. $ZnSO_{4(aq)}$ is placed in a copper vessel
• B. $AgNO_3$ solution is stirred with a copper spoon
• C. Conc. $HNO_3$ is stored in a platinum vessel
• D. gold ornaments are washed with dil $HCl$

Answer 1

Answer: (B)

$AgNO_3$ solution is stirred with a copper spoon

Answer 2

Platinum and gold lie at the bottom of the reactivity series. Thus it does not react with $HNO _{3}$ and $HCl$. Again, $Zn$ is more reactive than copper. Thus, copper will be displaced by $Zn$, if $ZnSO _{4}$ is placed in a copper vessel. But $Ag ^{+}$ is less reactive than copper. Thus, copper will displace silver. The corresponding reaction is:

$2 AgNO _{3}+ Cu \rightarrow Cu \left( NO _{3}\right)_{2}+2 Ag$