Which of the following combinations led to a precipitation reaction?

1. sodium phosphate and sodium iodide

2. lead nitrate and nitric acid

3. silver nitrate and aluminum sulfate

4. sodium phosphate and silver nitrate

(3) Silver Nitrate and Aluminium Sulfate

Explanation:

Silver nitrate and aluminium sulphate reacts to form Aluminium nitrate and silver sulfate.

The reaction is shown below:

6AgNO₃ (aq) + Al₂ (SO₄) ₃ (aq) → 2Al (NO₃) ₃ (aq) + 3Ag₂SO₄ (S)

From the balanced equation we can see that Ag₂SO₄ or silver sulfate is the precipitate formed.

Aluminium sulfate and silver nitrate both are chemical compounds. There are many reactions that uses net ionic equation like acid-base neutralization reaction, redox reaction, double displacement reaction etc.