A carbon compound contains 12.8% carbon 2.1% Hydrogen 85.1% bromine. The molecular weight of the compound is 187.9 calculate the molecular formula.

Empirical formula = CH₂Br
Empirical formula weight
= 12 + (2 × 1) + 80 = 94
The molecular weight =187.9 (given)
$\mathrm{n}=\frac{\text{ molecular weight }}{\text{ empirical formula weight }}=\frac{187.9}{94}=2$
Molecular formula = (Empirical formula)_n
${\left({\mathrm{CH}}_2\mathrm{Br}\right)}_2={\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{Br}}_2$