What are the values of $\Delta H_{mix}$ and $\Delta V_{mix}$ for an ideal solution?

In a binary ideal solution of liquids $A$ and $B$ at a constant temperature,the mole fraction of $B$ in the liquid phase is $0.4$ and in the vapor phase is $0.25$. If $P_B^o = 40 \ mm \ Hg$,then the vapor pressure of pure liquid $A$ at that temperature is .......... $mm \ Hg$.

Assuming ideal behaviour,the enthalpy and volume of mixing of two liquids respectively,are

Liquid $M$ and liquid $N$ form an ideal solution. The vapour pressures of pure liquids $M$ and $N$ are $450 \ mmHg$ and $700 \ mmHg,$ respectively at the same temperature. Then the correct statement is: ( $x_M =$ mole fraction of $M$ in solution; $x_N =$ mole fraction of $N$ in solution; $y_M =$ mole fraction of $M$ in vapour phase; $y_N =$ mole fraction of $N$ in vapour phase)

Which of the following is true when components forming an ideal solution are mixed?

The formation of a binary solution is considered as follows:
$(1)$ Pure solvent enthalpy $\Delta H_1$ (separated)
$(2)$ Pure solute enthalpy $\Delta H_2$ (separated)
$(3)$ Pure solvent + Pure solute $\to$ Solution $\to$ Enthalpy $\Delta H_3$
If $......$ then the resulting solution is ideal.