If copper metal is heated over a flame, it develops a coating. What is the colour and composition of this coating?

"$A$ solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed".
$(i)$ Translate the above statement into a chemical equation.

Three beakers labelled as $A$,$B$ and $C$ each containing $25 \, mL$ of water were taken. $A$ small amount of $NaOH$,anhydrous $CuSO_4$ and $NaCl$ were added to the beakers $A$,$B$ and $C$ respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers $A$ and $B$,whereas in case of beaker $C$,the temperature of the solution falls. Which one of the following statement$(s)$ is(are) correct?
$(i)$ In beakers $A$ and $B$,exothermic process has occurred.
$(ii)$ In beakers $A$ and $B$,endothermic process has occurred.
$(iii)$ In beaker $C$ exothermic process has occurred.
$(iv)$ In beaker $C$ endothermic process has occurred.

State three applications of a decomposition reaction.

State one industrial application of the reduction process.

Identify the type of reactions in each of the following reactions:
$(i)$ $CaCO_{3} \xrightarrow{\text{Heat}} CaO + CO_{2}$
$(ii)$ $AgNO_{3}(aq) + NaCl(aq) \longrightarrow AgCl(s) \downarrow + NaNO_{3}(aq)$