A. Under nonstandard conditions, the molar volume of gas at standard temperature and pressure cannot be used to calculate the amount of 2.24L hydrogen chloride, so A is wrong;

B. 1mol methane contains 10mol electrons, and the number of electrons contained is 10NA, so b is correct;

C. When iron ions are partially hydrolyzed, the iron ions contained in the solution are less than 0. 1mol, and the number of iron ions contained in the obtained solution is less than 0. 1NA, so c is wrong;

D. In the barium hydroxide solution with pH= 13 at room temperature, the concentration of hydroxyl ions is 0. 1mol/L, so the amount of substances containing hydroxyl ions in the barium hydroxide solution is 0. 1mol, and the solution contains 0./kloc-0.

So choose B.