Which of the following reactions is a neutralization reaction ?

1. When zinc reacts with dilute HCl
2. Reaction between barium chloride solution and dilute H₂SO₄
3. When carbon burns in air
4. Sodium hydroxide reacts with dilute H₂SO₄

Which of the following oxides produces salt upon reacting with sodium hydroxide?

1. Na₂O
2. CaO
3. NO
4. ZnO

The gas produced when iron metal reacts with dilute hydrochloric acid is:

1. oxygen
2. hydrogen
3. chlorine
4. water vapour

When copper metal is added to a solution of silver nitrate, the colour of the solution changes to blue. This shows:

1. copper is less reactive than silver
2. copper is more reactive than silver
3. both are equally reactive
4. none of the above