The compound $X$ on heating gives a colourless gas. The residue is dissolved in water to obtain $Y$ . Excess ${\rm{C}}{{\rm{O}}_2}$ is bubbled through aqueous solution of $Y,Z$ is formed. $Z$ on gentle heating gives back $X$ . The compound $X$ is:

${\rm{N}}{{\rm{a}}_2}{\rm{C}}{{\rm{O}}_3}$

${\rm{CaS}}{{\rm{O}}_4} \cdot 2{{\rm{H}}_2}{\rm{O}}$

${{\rm{K}}_2}{\rm{C}}{{\rm{O}}_3}$

NEET UG CHEMISTRY MCQ: S-BLOCK ELEMENTS

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Analyzing +4 | -1

The compound

X

on heating gives a colourless gas. The residue is dissolved in water to obtain

Y

. Excess

\mathrm{C}{\mathrm{O}_2}

is bubbled through aqueous solution of

Y,Z

is formed.

Z

on gentle heating gives back

X

. The compound

X

is:

View answer and explanation

Correct option: A

\mathrm{CaC}{\mathrm{O}_3}

Option A (

\mathrm{CaC}{\mathrm{O}_3}

) is correct because it decomposes to give

CO_2

, and the residue dissolves in water to form

Ca(OH)_2

, which reacts with excess

CO_2

to form

Ca(HCO_3)_2

, which on heating gives back

CaCO_3