A reddish-brown fume which is formed by the thermal decomposition of copper nitrate is:

Identify the salt Q from the following observation:

Salt Q is white in colour. On strong heating, it produces buff-yellow residue and liberates a reddish-brown gas. Solution of salt Q produces chalky white insoluble precipitate with an excess of ammonium hydroxide.

Identify the salt P from the following observations:

Salt P has light bluish-green colour. On heating, it produces a black coloured residue. Salt P produces brisk effervescence with dilute $\mathrm{HCl}$ and the gas evolved turns lime water milky, but no action with acidified potassium dichromate solution.

Identify the salt R from the following observation:

Salt R is black in colour. On reacting with concentrated $\mathrm{HCl}$, it liberates a pungent greenish-yellow gas which turns moist starch iodide paper blue-black.

State one relevant observation for the following reactions:

• Zinc carbonate is heated strongly.

Observe the reaction and identify the reactant and the product.

$2{\mathrm{PbO}}_2\to 2\mathrm{PbO}+{\mathrm{O}}_2$

Iron $\left(\mathrm{I}\mathrm{I}\mathrm{I}\right)$ chloride is prepared by passing pure dry chlorine gas over heated iron.

Write the chemical equation for the preparation of chlorine from concentrated hydrochloric acid.

Match the following:

Identify the type of reaction:

$2{\mathrm{PbO}}_2\to 2\mathrm{PbO}+{\mathrm{O}}_2$

From the list provided below choose the ones that match the description given.
Ferrous sulphate, Copper carbonate, Triferric tetroxide, Trilead tetroxide, Sulphur dioxide, Carbon dioxide, Lead nitrate, Zinc nitrate, Oxygen, Nitrogen.

A mixed oxide which liberates oxygen on heating.