Write the chemical equation of the reaction with an example in which a change in temperature 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 the balanced chemical equations for the following reactions and identify the type of reaction in each case.
$(a)$ Ethanol is warmed with ethanoic acid to form ethyl acetate in the presence of concentrated $H_2SO_4$.
$(b)$ Ethene is burnt in the presence of oxygen to form carbon dioxide, water and releases heat and light.

$(a)$ Define corrosion.
$(b)$ What is corrosion of iron called?
$(c)$ How will you recognise the corrosion of silver?

On heating blue coloured powder of copper $(II)$ nitrate in a boiling tube,copper oxide (black),oxygen gas and a brown gas $X$ is formed.
$(a)$ Identify the type of reaction.
$(b)$ What could be the $pH$ range of an aqueous solution of the gas $X$?

$(a)$ Classify the following chemical reactions as exothermic or endothermic:
$(i)$ Electrolysis of water
$(ii)$ Burning of natural gas
$(iii)$ Decomposition of calcium carbonate
$(iv)$ Burning of magnesium ribbon in air.