Question

The empirical formula of a gaseous compound is $C{H}_2$. The density of the compound is $1.25$ g/L at STP. The molecular formula of the compound is:

• A. $C_2{H}_4$
• B. $C_3{H}_6$
• C. $C_6{H}_{12}$
• D. $C_4{H}_8$

Answer 1

The correct option is A $C_2{H}_4$

The density is $1.25$ g/L.
$\therefore$ $1$ L $\equiv$ $1.25$ g.

As we know that 22.4 L corresponds to 1 mole of a gas,

$22.4$ L $\equiv$ $1.25\times 22.4=28=$ Molecular weight.

Let the Molecular Formula be $C_x{H}_{2x}$

So, $28=12x+2x=14x$.

we get, $x=2$

Therefore, the compound is $(C{H}_2{)}_x=C_2{H}_4$