Question

Which of the following statements is/are correct?

• A. $\text{Equivalent mass of}B{r}_3{O}_8\text{in the given reaction is 23}B{r}_3{O}_8+I^{-}+H^{+}\to B{r}_2+I_2+H_{2}O$
• B. $\text{In case of oxalic acid}\left(H_2{C}_2{O}_4\right)\text{the average oxidation number and individual oxidation number of Carbon have the same value}$
• C. $\text{In case of iodimetric titration KI is made to react with an oxidising agent and the liberated}{I}_2\text{gas is titrated with hypo solution}$
• D. $3Cl{O}^{-}\left(aq\right)\to Cl{O}_3^{-}\left(aq\right)+2C{l}^{-}\left(aq\right)$ is an example of combination reaction.

Answer 1

Answer: (A), (B)

The correct options are
A $\text{Equivalent mass of}B{r}_3{O}_8\text{in the given reaction is 23}B{r}_3{O}_8+I^{-}+H^{+}\to B{r}_2+I_2+H_{2}O$
B $\text{In case of oxalic acid}\left(H_2{C}_2{O}_4\right)\text{the average oxidation number and individual oxidation number of Carbon have the same value}$

(A) n.f. of $B{r}_3{O}_8=3(\frac{16}{3}-0)=16\therefore$ equivalent mass $=\frac{M}{16}=\frac{368}{16}=23$
(B) In case of oxalic acid $\left(H_2{C}_2{O}_4\right)$ the average oxidation number and individual oxidation number of carbon have the same value equal to + 3.
Average oxidation number is calculated using a simple formula assuming the oxidation of $C$ as $x$ and $H$ shows $+1$ and $O$ shows $-2$ so by calculation we get$+3$ and individual oxidation number is deduced from structure of the compound.
(C) In Case of iodometic titration KI is made to react with an oxidising agent and the liberated $I_2$ gas is titrated with hypo solution so due to this it is incorrect.
(D)
$3\stackrel{+1}{C}l{O}^{-}\left(aq\right)\to \stackrel{+5}{C}l{O}_3^{-}\left(aq\right)+2\stackrel{-1}{C}{l}^{-}\left(aq\right)$
$Cl$ atom is getting oxidized $(C{l}^{+}\to C{l}^{5+}+4e^{-})$
Also, the same $Cl$ atom is getting reduced
$(C{l}^{+}+2e^{-}\to C{l}^{-}).$
Such reactions are called disproportionation reactions.