Q12 / 125 · BITSAT 2011 · Chemistry
When a crystal of caustic soda is exposed to air, a liquid layer is deposited because :
- ACrystal loses water
- Correct answerBCrystal absorbs moisture and $\mathrm{CO}_{2}$
- CCrystal melts
- DCrystal sublimes
Solution
It is hygroscopic and deliquescent and hence absorbs moisture and $\mathrm{CO}_{2}$ to form $\mathrm{Na}_{2} \mathrm{CO}_{3}$
$$
2 \mathrm{NaOH}+\mathrm{CO}_{2} \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}
$$
Hence, the correct answer is option: 'B'.