Question

What is the molecular formula of an alkene and an alkane with 20 carbon atoms?

Answer 1

THE FORMULA FOR THE ALKANE

Cn H 2N+2

C20 H42  ( Icosane )


THE FORMULA FOR ALKENE IS
Cn H2n

C20 H40 ( Icosene )

Answer 2

alkane general formula  is $C_{n} H_{2n+2}$ 

apply n = 20

$C_{20} H_{2(20) + 2}$

$C_{20} H_{42}$

----------------------------------------------------------------------
GENERAL FORMULA OF ALKENE = $C_{n} H_{2n}$

$C_{20} H_{40}$

-----------------------