Pblock Elementsii Result Question 2
2. Chlorine on reaction with hot and concentrated sodium hydroxide gives
(a) $\mathrm{Cl}^{-}$and $\mathrm{ClO}^{-}$
(b) $\mathrm{Cl}^{-}$and $\mathrm{ClO}_3^{-}$
(c) $\mathrm{ClO}_3^{-}$and $\mathrm{ClO}_2^{-}$
(d) $\mathrm{Cl}^{-}$and $\mathrm{ClO}_2^{-}$
(2019 Main, 12 Jan II)
Show Answer
Answer:
Correct Answer: 2. ( b )
Solution:
- Halogens form halates and halides with hot and concentrated solution of $\mathrm{NaOH}$ as :
$3 X_2+6 \mathrm{NaOH} \longrightarrow 5 \mathrm{NaX}+\mathrm{NaX} \mathrm{O}_3+3 \mathrm{H}_2 \mathrm{O}$
$\mathrm{So}, \mathrm{Cl}_2$ will also give $\mathrm{Cl}^{-}$
(as $NaCl$ ) and $\mathrm{ClO}_3^{-}$
(as $ \mathrm{NaClO} _3 $ ) in the above reaction.
Thus, option (b) is correct.
Note When halogens react with cold and dilute solution of $\mathrm{NaOH}$, hypohalites and halides are produced as:
$\mathrm{X}_2+2 \mathrm{NaOH} \longrightarrow \mathrm{NaX}+\mathrm{NaXO}+\mathrm{H}_2 \mathrm{O}$
BETA
