Question

A white solid $X$ on heating gives a white solid $Y$ and an acidic gas $Z$. Gas $Z$ is also given out when $X$ reacts with an acid. The compound $Y$ is also formed if caustic soda is left open in the atmosphere. $X$, $Y$ and $Z$ are

	$X$	$Y$	$Z$
(a)	$NaHCO_3$	$Na_2CO_3$	$CO_2$
(b)	$Na_2CO_3$	$NaOH$	$CO_2$
(c)	$Na_2CO_3$	$NaHCO_3$	$CO_2$
(d)	$NaOH$	$NaHCO_3$	$CO_2$

• A. a
• B. b
• C. c
• D. d

Answer 1

Answer: (A)

$\underset{(X)}{2 NaHCO _3} \rightarrow \underset{(Y)}{Na _2 CO _3}+ \underset{(Z)}{CO _2}+ H _2 O$
$\underset{(X)}{NaHCO _3}+ HCl \rightarrow NaCl + \underset{(Z)}{CO _2}+ H _2 O$
$2 NaOH +\underset{\text { (atmosphere) }}{ CO _2} \rightarrow \underset{( Y )}{ Ca _2} Na _2+ H _2 O$