Question

What is the percentage composition of $CaB{r}_2$? (Atomic weights: Ca=40, Br=80)

• A. 10% Ca and 90% Br
• B. 20% Ca and 80% Br
• C. 25% Ca and 75% Br
• D. 33% Ca and 67% Br
• E. 50% Ca and 50% Br

Answer 1

The correct option is B 20% Ca and 80% Br

Molecular weight of compound $=40+2\times 80=200$

$\%Ca=\left(40/200\right)\times 100=20\%$

So, $\%Br=80\%$.