Which of the following statements about bonding is correct?
- AAll the atoms in $\text{CH}_4$, $\text{NH}_3$ and $\text{H}_2\text{O}$ molecules have noble gas electronic configurations.
- BCalcium chloride is a covalent molecule.
- CGroup I metals gain electrons when they bond with Group VII elements.
- DOxide ions in calcium oxide are positively charged.