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

Write true or false for the following statement:
Due to corrosion, iron gets a brown coating, copper gets a green coating, and silver gets a black coating.

Name the oxidising and reducing agent in the following reaction:
$CuO + H_{2} \longrightarrow Cu + H_{2}O$

You could have noted that when copper powder is heated in a china dish, the surface of copper powder becomes coated with black coloured substance.
$(i)$ Why has this black coloured substance formed?
$(ii)$ What is this black substance?
$(iii)$ Write the chemical equation of the reaction that takes place.

Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
$(a)$ Nitrogen gas is treated with hydrogen gas in the presence of a catalyst at $773 \ K$ to form ammonia gas.
$(b)$ Sodium hydroxide solution is treated with acetic acid to form sodium acetate and water.

Write a balanced chemical equation for the reaction in which phosphorus burns in chlorine to form phosphorus pentachloride.