Question

0.2 mole of an alkane on complete combustion gave 26.4g of carbon dioxide. Find the molecular weight of alkane :

• A. $16$
• B. $30$
• C. $44$
• D. $58$

Answer 1

The correct option is C $44$

$O.2$ mole of alkane gives 26.4 g of $C{O}_2$

Hence, 1 mole gives $\frac{26.4}{O.2}g$ of $C{O}_2$

$=132g$ of $C{O}_2$

1 mole of $C{O}_2$ is 44 gm

132 of $C{O}_2$ means 3 moles

$\therefore$ Alkane has 3 carbon atom and therefore, it is providing $3C{O}_2$

Formula is $C_3{H}_8$ (propane)

Molecular weight of $C_3{H}_8$ is 44.

Hence the correct option is C.