Which of the following is not equal to zero for an ideal solution?

Liquids $A$ and $B$ form an ideal solution in the entire composition range. At $350 \ K$,the vapour pressures of pure $A$ and pure $B$ are $7 \times 10^3 \ Pa$ and $12 \times 10^3 \ Pa$,respectively. The composition of the vapour in equilibrium with a solution containing $40 \ \text{mole percent}$ of $A$ at this temperature is

$2 \ moles$ each of liquids $A$ and $B$ are dissolved to form an ideal solution. What will be the mole fraction of $B$ in the vapour phase? Given: $P_A^o = 120 \ torr, P_B^o = 80 \ torr$

When $25 \ mL$ of acetone is mixed with $25 \ mL$ of ethanol,the volume of the resulting solution will be ...........

Which of the following pairs does not form an ideal solution?

If liquids $A$ and $B$ form an ideal solution,then: