At $80^{\circ }\text{C}$, the vapour pressure of pure liquid ‘A’ is $520\text{mm Hg}$ and that of pure liquid ‘B’ is $1000\text{mm Hg}$. If a mixture solution of ‘A’ and ‘B’ boils at $80^{\circ }\text{C}$ and $1\text{atm}$ pressure, the amount of ‘A’ in the mixture is ($1\text{atm}=760\text{mm Hg}$):

1. A
   $52\text{mol percent}$
2. B
   $34\text{mol percent}$
3. C
   $48\text{mol percent}$
4. D
   $50\text{mol percent}$