What is enthalpy change and volume change of mixing of two components forming an ideal solution?

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

The plot of total vapour pressure as a function of mole fraction of the component of an ideal solution formed by mixing liquids X and Y is

If DeltaH is the enthalpy change and DeltaU the change in internal energy accompanying a gaseous reaction, then

The enthalpy change of the following reaction