Question

Which substance serves as reducing agent in the following reaction?
$14H^{+}+C{r}_2{O}_7^{2-}+3Ni\to 2C{r}^{3+}+7H_{2}O+3N{i}^{2+}$

• A. $H_{2}O$
• B. Ni
• C. $H^{+}$
• D. $C{r}_2{O}_7^{2-}$

Answer 1

The correct option is B Ni

The element undergo oxidation itself and reduces others is known as reducing agent.
$14H^{+}+\stackrel{+6}{C}{r}_2{O}_7^{2-}+3\stackrel{0}{N}i\to 2\stackrel{+3}{C}{r}^{3+}+7H_{2}O+3\stackrel{+2}{N}{i}^{2+}$
In this reaction oxidation number of Ni changes from 0 to +2 thus Ni undergoing oxidation and hence Ni acts as a reducing agent.