Write true or false for the following statement:
The thermal decomposition reaction of calcium sulphate (gypsum) is used in black and white photography.

When potassium iodide solution is added to a solution of lead $(II)$ nitrate in a test tube,a precipitate is formed.
$(i)$ Write a balanced chemical equation for this reaction.
$(ii)$ What type of reaction is this?

$A$ small amount of quicklime is added to water in a beaker.
$(a)$ Name and define the type of reaction that has taken place.
$(b)$ Write the balanced chemical equation for the above reaction. Write the chemical name of the product obtained.
$(c)$ State two observations that you will make in the reaction.

The substances which get oxidised easily can be kept for longer duration by:

Give reasons for the following:
$(i)$ All decomposition reactions are endothermic reactions.
$(ii)$ Colour of copper sulphate solution changes when an iron nail is dipped in it.
$(iii)$ Respiration is an exothermic reaction.

Explain,giving chemical equations,any two uses of chemical decomposition reactions in industry.