Rubidium and strontium are both located in Period 5 of the Periodic Table. Rubidium is in Group I. Strontium is in Group II. Which of the following statements about these elements is correct?
- AEach element has five electrons in its outer electron shell.
- BThe atomic number of rubidium is greater than the atomic number of strontium.
- CRubidium forms the $\text{Rb}^+$ ion; strontium forms the $\text{Sr}^{2+}$ ion.
- DElectrolysis of molten rubidium chloride and of molten strontium chloride produces hydrogen.