Arrange the following in increasing the amount of nitrogen in the fertilizers:
(A) Ammonium sulphate
(B) Ammonium nitrate
(C) Ammonium chloride
(D) Calcium ammonium nitrate
If 0.01 mol of $\mathrm{P_4O_{10}}$ is removed from 0.1 mol, then the remaining molecules of $\mathrm{P_4O_{10}}$ will be:
An element has two isotopes having atomic masses 10 and 15 u, respectively. If the percent abundance of lighter isotopes is 80%, then the average atomic mass of the element is: