Question

An organic compound contains 66% $C$, 13.3% $H$ and the remaining is $O$. Its vapour density is 37. The possible number of isomers of all types for the compound is:

• A. 6
• B. 7
• C. 5
• D. 8

Answer 1

The correct option is B 7

100 g of organic compound contains 66 g of $C$ and 13.3 g of hydrogen. The remaining 20.7 g corresponds to oxygen.

The molar masses of $C,H$ and $O$ are 12, 1 and 16 g/mol respectively.
100 g of organic compound contains 5.5 g moles of $C$, 13.3 moles $H$ and 1.3 moles oxygen

The molar mass is two times vapour density. It is $2\times 37=74$ g/mol

74 g of the organic compound contains 4 moles of $C$, 10 moles of $H$ and 1 mole of $O$.

Thus, the molecular formula of the compound is $C_4{H}_{10}O$.

It can have 7 different isomers. These are shown above.