If two pure liquid constituents are mixed in any proportion to give an ideal solution, there is no change in

An ideal solution is that where the components behaves like pure components.
For an ideal solution the heat of mixing or enthalpy change and volume change due to mixing is zero.
Since, volume change of mixing $$ = {V^t}\left( {T,P} \right) - \sum {} {x_i}{V_i}\left( {T,P} \right).$$
Where $${V^t}$$ $$=$$ total molar volume of the solution at temperature $$T,$$ pressure $$P.$$
\[{{V}_{i}}\] $$=$$ molar volume of species when existed as pure species at same $$T,\,P.$$
From summability: \[{{V}^{t}}=\sum{{}}{{x}_{i}}{{{\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{V}}}_{l}}\]
Where \[{{{\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{V}}}_{l}}=\] partial molar volume since for ideal solution
\[\sum{{}}{{x}_{i}}{{{\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{V}}}_{l}}=\sum{{}}{{x}_{i}}{{V}_{i}}\left( T,P \right)\Rightarrow \]     Volume change of mixing $$= 0$$
Similarly, enthalpy change of mixing or heat of mixing $$= 0$$