http://i68.tinypic.com/2e1u5x4.jpg - question 10 why is the answer (c)..?

10.
A. False
As the two flasks are identical, Gases X and Y are in the same temperature, pressure and volume. Therefore, the numbers of gaseous particles in the two bottles are equal.

B. False
As the two flasks are identical, Gases X and Y are in the same temperature, pressure and volume. Therefore, the numbers of moles gaseous particles in the two bottles are equal.

C. True
As numbers of moles of particles in the two flasks are equal, but mass of Gas A is greater than that of Gas B. Therefore, the molar mass of gas A is greater than that of gas B.

D. False
Under the same conditions, the molar volumes of the two gases are equal.

...... The answer is : C. The molar mass of gas particles in bottle A is greater than the molar mass of gas particles in bottle B.