A carbon compound contains 12.8% of carbon, 2.1% of hydrogen and 85.1% bromine . The molecule mass of compound is 187.9. calculate the molecular formula of the compound (Atomic mass H=1.008,C=12,Br=79.9)

Options

A. `CH_(3)Br`
B. `CH_(2)Br_(2)`
C. `C_(2)H_(4)Br_(2)`
D. `C_(2)H_(3)Br_(3)`

Answer

C

Explanation

Number of 'C' atoms `=(%)/(100)xx("Molecular mass")/("Atomic mass")`
`(12.8)/(100)xx(187.9)/(12)=2`
Number of 'H' atoms `=(%)/(100)xx("Molecular mass")/("Atomic mass")`
`=(2.1)/(100)xx(187.9)/(1.008)=4`
Number of 'Br' atoms `=(%)/(100)xx("Molecular mass")/("Atomic mass")`
`=(85.1)/(100)xx(187.9)/(79.9)=2`
Molecular formula `=C_(2)H_(4)Br_(2)`.