Question

$6\times {10}^{-3}$ moles of $K_{2}C{r}_2{O}_7$ reacts completely with $9\times {10}^{-3}$ moles of $X^{n+}$ to give $X{O}_3^{-}$ and $C{r}^{3+}$. The value of n is:

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is A 1

$K_2{\stackrel{6+}{Cr}}_2{O}_7+X^{n+}\to \stackrel{5+}{X}{O}_3^{-}+C{r}^{3+}$
$6\times {10}^{-3}\times 6=(5-n)\times 9\times {10}^{-3}$
$\Rightarrow n=1$