Question

The measured molar volume of gas A was found to be 10% smaller than when it behave ideally.comment on this observation.

Answer 1

From: http://wwwchem.csustan.edu/chem1102/molarvol.htm
"The ideal gas law, PV = nRT, gives an accurate description of the behaviour of real gases at low pressures and at temperatures which are high relative to the boiling point. The ideal gas law is based on the assumption that the molecules experience no intermolecular forces and that the molecules occupy no volume. These assumptions are valid at low pressure and high temperature since under these conditions the molecular density is low. The molecules are too far apart to "feel" attractive forces exerted by other molecules. Furthermore, since the molecules are far apart, the volume occupied by the molecules is negligible compared to the total volume occupied by the gas."

Therefore, if the measured molar volume is 10% smaller, then I would guess that either the gas is NOT at a low pressure or it is at a temperature that is NOT high relative to its boiling point (or both). Under these conditions, the gas molecules ARE close enough to "feel" the attractive forces exerted by other molecules and, hence, the gas volume would become smaller.