Question

Which of the following reaction produces a base?

• A. Burning of metal in air
• B. Adding water to a metal oxide.
• C. Reaction between an acid and base
• D. Heating metal carbonates

Answer 1

The correct option is B

Adding water to a metal oxide.

- Metal oxides react with water to form bases by associating with hydroxyl ion present in water. For example, the chemical reaction between calcium oxide and water:

$\text{CaO}\text{(s)}+{\text{H}}_2\text{O}\text{(l)}\to {\text{Ca(OH)}}_2\text{(aq)}$

- Basic oxides can be made by the direct combination of metals with oxygen.
- Heating of metal carbonates produces metal oxide and releases ${\text{CO}}_2$ gas.
- Salt and water are formed when acid reacts with base.