Some Basic Concepts of Chemistry - Result Question 13 — JEE PYQ Chapterwise

Answer:

Correct Answer: 28. (a)

Solution:

28. Unlike other metal carbonates that usually decomposes into metal oxides liberating carbon dioxide, silver carbonate on heating decomposes into elemental silver liberating mixture of carbon dioxide and oxygen gas as :

$\begin{array}{cc} \mathrm{Ag}_2 \mathrm{CO}_3(s) \xrightarrow{\text { Heat }} & 2 \mathrm{Ag}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \\ \mathrm{MW}=276 \mathrm{~g} & 2 \times 108=216 \mathrm{~g} \end{array}$

Hence, 2.76 g of $\mathrm{Ag}_2 \mathrm{CO}_3$ on heating will give $\frac{216}{276} \times 2.76=2.16 \mathrm{~g} \mathrm{Ag}$ as residue.