Liquid air is divided into its gases by fractional distillation. The boiling points of four gases are given. Which gas is monoatomic and also a liquid at $-200\,^{\circ}\text{C}$?
- Aargon (boiling point $-186\,^{\circ}\text{C}$)
- Bhelium (boiling point $-269\,^{\circ}\text{C}$)
- Cneon (boiling point $-246\,^{\circ}\text{C}$)
- Dnitrogen (boiling point $-196\,^{\circ}\text{C}$)