Question

A certain compound $X$ imparts a golden yellow flame. When zinc powder is heated with a concentrated solution of $X$, $H_2$ gas is evolved. $X$ combines with $C{O}_2$ to gave a salt $Y$. $Y$ is a hydrated salt which on reaction with $HCl$ or an excess of $C{O}_2$ gives another salt $Z$ which is an important part of baking powder. Identify $X,Y$ and $Z$.

• A. $X-NaOH,Y-N{a}_{2}C{O}_3,Z-NaHC{O}_3$
• B. $X-HCl,Y-NaOH,Z-NaHC{O}_3$
• C. $X-KOH,Y-K_{2}C{O}_3,Z-KHC{O}_3$
• D. $X-NaCl,Y-N{a}_{2}C{O}_3.Z-NaOH$

Answer 1

The correct option is A $X-NaOH,Y-N{a}_{2}C{O}_3,Z-NaHC{O}_3$

Sodium hydroxide when heated on bunsen burner it impart golden yellow flame.when zinc powder is heated with concentrated solution of sodium hydroxide ($X$), hydrogen gas is evolved. Sodium hydroxide ($X$) combines with carbon dioxide to give sodium cabonate ($Y$). Sodium carbonate is a hydrated salt which on reaction with $HCl$ or excess of carbon dioxide gives another salt sodium bicarbonate. The reactions are given below:

$Zn+2NaOH\left(X\right)\to N{a}_{2}Zn{O}_2+H_2$
$2NaOH\left(X\right)+C{O}_2\to N{a}_{2}C{O}_3\to H_{2}O$
$N{a}_{2}C{O}_3\left(Y\right)+HCI\to +NaHC{O}_3\left(Z\right)+NaC1$
$N{a}_{2}C{O}_3\left(Y\right)+C{O}_2+H_{2}O\to 2NaHC{O}_3\left(Z\right)$