Question

What is the colour of precipitate formed when lead nitrate reacts with potassium iodide?

• A. Green
• B. Black
• C. Blue
• D. Yellow

Answer 1

Correct option: (A)

• When Lead nitrate$\left(Pb\right(N{O}_3{)}_2)$ reacts with potassium iodide$\left(KI\right)$, leading to the formation of a yellow precipitate of lead iodide$\left(Pb{I}_2\right)$ and potassium nitrate$\left(KN{O}_3\right)$.​
• The balanced chemical reaction can be represented as:
• $Pb\left(N{O}_3{)}_2\right(aq)+2KI(aq)\to Pb{I}_2(\downarrow )+2KN{O}_3(aq)$
• This is an example of a double displacement reaction because the lead and potassium exchange their anions to give lead iodide and potassium nitrate.

Hence, the correct option is A.