i. What is observ

i. When lead nitrate reacts with potassium iodide, it forms a yellow coloured precipitate of lead iodide along with potassium nitrate.

ii. This type of reaction is a double displacement reaction.

iii. [PbNO₃]₂ + 2KI → 2KNO₃ + PbI₂

Here,

PbNO₃ is lead nitrate.

KI is potassium iodide.

KNO₃ is potassium nitrate.

PbI₂ is lead iodide.

OR

i. X is Cu.

Y is CuO.

ii. This a redox chemical reaction. Here, copper gets oxidised by heating to copper oxide, and hydrogen reduces copper oxide back to copper.

iii. Cu + O₂ → 2CuO

CuO + H₂ → Cu + H₂O