Answer the following question briefly:
Observe the melting and boiling point of the substance A, B and C given in the following table:
| Substance | Melting point (°C) | Boiling point (°C) |
| A | - 210 | - 196 |
| B | 250 | 700 |
| C | - 20 | 90 |
a. State the physical state of substance A, B and C at room temperature (200°C).
i. Physical state of substance "A" is
ii. Physical state of substance "B" is
iii. Physical state of substance "C" is
b. Define melting point.
A melting point is the specific temperature at which a at atmospheric pressure.
The melting point of ice is .