MCQ
Colour of $CrO_4^{^{2 - }}(aq.)$ is not changed by
- Adil. $HCl$
- ✓$NH_3$ solution
- C$CH_3COOH$
- D$NO_2$ gas
✓
Answer
Correct option: B.
$NH_3$ solution
b
$\mathop {CrO_4^{2 - }(aq.)}\limits_{(yellow)} \underset{\begin{subarray}{l}
pH > 7 \\
(Basic)
\end{subarray} }{\overset{\begin{subarray}{l}
(Acidic) \\
pH < 7
\end{subarray} }{\longleftrightarrow}}\mathop {C{r_2}O_7^{2 - }(aq.}\limits_{(Orange)} )$
$\mathop {CrO_4^{2 - }(aq.)}\limits_{(yellow)} \underset{\begin{subarray}{l}
pH > 7 \\
(Basic)
\end{subarray} }{\overset{\begin{subarray}{l}
(Acidic) \\
pH < 7
\end{subarray} }{\longleftrightarrow}}\mathop {C{r_2}O_7^{2 - }(aq.}\limits_{(Orange)} )$
$NH_3$ being basic in solution, does not change yellow colour of $CrO_4\,^{2-}(aq.)$ .
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