In which of the following chemical equations,the abbreviations represent the correct states of the reactants and products involved at reaction temperature?

Which among the following statement$(s)$ is(are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to
$(i)$ the formation of silver by decomposition of silver chloride
$(ii)$ sublimation of silver chloride
$(iii)$ decomposition of chlorine gas from silver chloride
$(iv)$ oxidation of silver chloride

Which among the following are physical or chemical changes?
$(a)$ Evaporation of petrol
$(b)$ Burning of Liquefied Petroleum Gas $(LPG)$
$(c)$ Heating of an iron rod to red hot
$(d)$ Curdling of milk
$(e)$ Sublimation of solid ammonium chloride

Give reasons for the following:
$(i)$ Keeping food in airtight containers helps in preventing rancidity.

Write true or false for the following statement: On heating the crystals of ferrous sulphate,the colour changes from green to grey.

What happens when a piece of $Zn$ metal is added to $CuSO_4$ solution?