(A) We can store copper sulphate in a silver vessel because silver is less reactive than copper,so no displacement reaction occurs. However,we cannot store silver nitrate solution in a copper vessel because copper is more reactive than silver and will displace silver from its salt solution.
$Cu(s) + 2AgNO_{3}(aq) \rightarrow Cu(NO_{3})_{2}(aq) + 2Ag(s)$
$(b)$ Nitric acid $(HNO_{3})$ is a strong oxidizing agent. When zinc reacts with dilute $HNO_{3}$,the hydrogen gas produced is immediately oxidized to water $(H_{2}O)$,while the nitric acid itself gets reduced to nitrogen oxides like $N_{2}O$,$NO$,or $NO_{2}$.
$(c)$ Tin is less reactive than zinc. Zinc is more reactive and can easily react with organic acids present in food,potentially contaminating it. Tin provides a protective,non-reactive layer that preserves the food.