Question

while heating the lead nitrate ----- yellow coloured substance is formed

Answer 1

When we heat the lead nitrate we get lead monoxide (PbO).
PbO is yellow when hot and white when cold.

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Hope you get it.

Answer 2

ANSWER:

The yellow coloured substance called Lead oxide is formed while heating lead nitrate.

EXPLANATION:

The reaction involves the decomposition reaction forming lead oxide, nitrogen dioxide and oxygen. The two coloured substance are formed, lead oxide as yellow coloured solid and nitrogen dioxide as brown colour gas.

Hence the final product formed in yellowed coloured solid of lead oxide, upon heating lead nitrate. The brown gas nitrogen di oxide evolves which has irritating smell. The same gas turns blue litmus red, proving its acidic nature.