An inert gas R is used to inflate weather balloons. Which statements about R are correct?
- Anumber of outer shell electrons in atoms of R: $2$; structure of gas R: diatomic molecules
- Bnumber of outer shell electrons in atoms of R: $2$; structure of gas R: single atoms
- Cnumber of outer shell electrons in atoms of R: $8$; structure of gas R: diatomic molecules
- Dnumber of outer shell electrons in atoms of R: $8$; structure of gas R: single atoms