Question

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Answer 1

Answer:

Let the formula of the hydrocarbon is

CnHm(see attachment)

Then total weight of 1mole this hydrocarbon is

(12n + m) gm

Now we know 1 mole gas takes 22.4 litres (NTP) of volume.

Here weight of 1 litre =2.68 gm

So weight of 1 mole =22.4* 2.68=60 gm

Thus we get { (12n +m) = 60}............ (1)

Now the hydrocarbon contains 80% carbon which means

Weight of carbon/total molecular weight =80%

$\frac{12n}{60} = \frac{80}{100}$

Or, n=(80*60)/(100*12) = 4

From equation (1)

m=60 - 12n = 60- 12*4 =12

So the formula is ( C4H12)