Write a balanced chemical equation with state symbols for the following reactions.

$(i)$ Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.

$(ii)$ Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Explain the "Reduction'' in terms of gain or loss of oxygen with two examples.

$Fe _{2} O _{3}+2 Al \rightarrow Al _{2} O _{3}+2 Fe$

The above reaction is an example of a 

Write the balanced equation for the following chemical reactions.

$(i)$ Hydrogen $+$ Chlorine $\to $ Hydrogen chloride

$(ii)$ Barium chloride $+$ Aluminium sulphate $\to $ Barium sulphate $+$ Aluminium chloride

$(iii)$ Sodium $+$ Water $\to $  Sodium hydroxide $+$ Hydrogen

Translate the following statements into chemical equations and then balance them.

$(a)$ Hydrogen gas combines with nitrogen to form ammonia.

$(b)$ Hydrogen sulphide gas burns in air to give water and sulpur dioxide.

$(c)$ Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.

$(d)$ Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.