Question

The percentage composition of $Cr$ in $K_{2}C{r}_2{O}_7$ is_________ $\%$.
(At. mass: $K=39u;Cr=52u;O=16u$ )

Answer 1

Answer: 35.37

Molar mass of $K_{2}C{r}_2{O}_7$
$=2\times (39)+2\times (52)+7\times (16)$
$=78+104+112=294gmo{l}^{-1}$
Percentage of $Cr=\frac{104}{294}\times 100=35.37\%$