Consider the following table
| Substitute | Meltig point / ºC | Boiling point / ºC |
| P | – 78 | -25 |
| Q | – 8 | 40 |
| R | – 6 | 150 |
| S | 44 | 280 |
Which of the substances is a liquid at room temperature and rapidly evaporates on exposure to air?
- P
-
Q
- R
- S
The correct answer is: B
Explanation
Q has slightly lower boiling point which when expose to air may evaporate rapidly.