For a binary liquid mixture at a fixed temperature, pure A has vapour pressure $200\mathrm{torr}$ and pure B has $100\mathrm{torr}$. For a liquid with $x_A=0.40$ the measured partial pressures are $p_A=100\mathrm{torr}$ and $p_B=75\mathrm{torr}$. Define the activity coefficient of a component as ${\gamma }_i=p_i/(x_i{p}_i^0)$. Which statements are correct?

1. AThe mixture can form a maximum-boiling azeotrope
2. BThe activity coefficient of A is $0.80$
3. CThe mixture shows positive deviation from Raoult's law
4. DThe mole fraction of A in the vapour is about $0.57$