The general formula for alkanes isC_nH_{2n +,}. 2. Write the general formulae for alkenes and alkynes.

The general formula for alkanes is C_nH_{2n + 2}. Since, an alkene contains two hydrogen atoms less than the corresponding alkane, therefore, the general formula for alkenes is C_nH_2n.

Further since an alkyne contains 2 hydrogen atoms less than the corresponding alkene, hence the general formula for alkynes is C_nH_2n _ ₂.