Which condition is not satisfied by an ideal solution?

Liquids $A$ and $B$ form an ideal solution for all compositions of $A$ and $B$ at $25^{\circ} C$. Two such solutions with $0.25$ and $0.50$ mole fractions of $A$ have total vapor pressures of $0.3 \ bar$ and $0.4 \ bar$,respectively. What is the vapor pressure of pure liquid $B$ in $bar$?

$A$ binary liquid solution is prepared by mixing $n$-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

On mixing $10 \ mL$ $CCl_4$ and $10 \ mL$ benzene,the total volume of solution is

$A$ and $B$ on mixing form an ideal solution at room temperature. Which of the following options is correct for this process?

Two liquids $A$ and $B$ form an ideal solution at temperature $T \ K$. At $T \ K$, the vapour pressures of pure $A$ and $B$ are $55 \ kNm^{-2}$ and $15 \ kNm^{-2}$ respectively. What is the mole fraction of $A$ in the solution of $A$ and $B$ in equilibrium with a vapour in which the mole fraction of $A$ is $0.8$?