MCQ
An alkane has a $C/H-$ ratio (by mass) of $5.1428$. Its molecular formula is
- A${C_5}{H_{12}}$
- ✓${C_6}{H_{14}}$
- C${C_8}{H_{18}}$
- D${C_7}{H_{10}}$
✓
Answer
Correct option: B.
${C_6}{H_{14}}$
b
(b) The ratio of $C/H$ in an alkane is $5.1428.$
(b) The ratio of $C/H$ in an alkane is $5.1428.$
Alkanes have General formula ${C_n}{H_{2n + 2}}$
The mass ratio of $\frac{C}{H}$ is $\frac{{12n}}{{2n + 2}}$ or $\frac{{6n}}{{n + 1}}$
$\frac{{6n}}{{n + 1}} = 5.1428$
$6n = 5.1428n + 5.1428 = 0.8572n + 5.1428$
$n = \frac{{5.1428}}{{0.8572}} = 6$
molecular formula $ = {C_6}{H_{2n + 2}} = {C_6}{H_{14}}$.
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