Give reasons for the following:
a. Ionic compounds in general have high melting and boiling points.
b. Highly reactive metals cannot be obained from their oxides by heating them with carbon.
c. Copper vessel get a green coat when left exposed to air in the rainy season.

Explanation

a. In ionic compounds the ions are held by strong electrostatic force of attraction hence the bond is very strong and require more energy to break. Therefore they have high melting and boiling points.
b. It is because these metals, themselves are strong reducing agents. Therefore carbon cannot be used as reducing agent.
c. Copper vessels reacts with `CO_(2)` and `O_(2)` and moisture to dorm green coloured basic copper carbonate.
`[CuCO_(3).Cu(OH)_(2)]`