Write the condensed formula of a linear alkane, whose molecular formula is C 20 H 42 .

Solution: Linear alkanes can be written in condensed form using the following formula: CH 3 (CH 2 ) n CH 3 , where n is the number of CH 2 in the molecule. The molecular formula of the problem has 20 carbons, two of them are for methyls, therefore, the condensed formula will have 18 CH 2 .

Condensed formula: CH 3 (CH 2 ) 18 CH 3