W, X, Y and Z are Group 2 elements: barium, calcium, magnesium and strontium, although not necessarily in that sequence. W reacts with dilute hydrochloric acid more quickly than Y does. The hydroxide of X is less soluble in water than the hydroxide of W. The sulfate of Y is the most soluble among the sulfates of W, X, Y and Z. At the same temperature, the carbonate of Z decomposes more slowly than the carbonate of W. What is the $M_r$ of the nitrate of W?
- A148.3
- B164.1
- C211.6
- D261.3