Transition and InnerTransition Elements - Result Question 14
15. Sodium salt of an organic acid ’ $X$ ’ produces effervescence with conc. $H _2 SO _4$. ’ $X$ ’ reacts with the acidified aqueous $CaCl _2$ solution to give a white precipitate which decolourises acidic solution of $KMnO _4 \cdot$ ’ $X$ ’ is
(2017 Main)
(a) $C _6 H _5 COONa$
(b) $HCOONa$
(c) $CH _3 COONa$
(d) $Na _2 C _2 O _4$
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Answer:
Correct Answer: 15. (d)
Solution:
The reaction takes place as follows
$ \begin{aligned} & \underset{(X)}{Na _2 C _2 O _4}+\underset{\text { (Conc.) }}{H _2 SO _4} \longrightarrow Na _2 SO _4+H _2 O \underset{\text { Effervescence }}{+CO \uparrow}+CO _2 \uparrow \\ & ~ \\ & \underset{(X)}{Na _2 C _2 O _4}+CaCl _2 \longrightarrow \underset{\text{White ppt.}}{CaC _2 O _4}+2 NaCl \\ & ~ \\ & 5 CaC _2 O _4+\underset{\text{Purple}}{2 KMnO _4}+8 H _2 SO _4 \longrightarrow K _2 SO _4+5 CaSO _4 \\ & ~ \\ &\hspace{40mm} +\underset{\text{Colourless}}{2 MnSO _4}+10 CO _2+8 H _2 O \\ \end{aligned} $
Hence, $X$ is $\mathrm{Na}_2 \mathrm{C}_2 \mathrm{O}_4$.
BETA
