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.
$(i)$ $BaC{l_{2\left( {aq} \right)}} + N{a_2}S{O_{4\left( {aq} \right)}}$ $\to $ $BaS{O_{4(s)}} + 2NaC{l_{\left( {aq} \right)}}$
$(ii)$ $NaO{H_{(aq)}} + HC{l_{(aq)}}$ $ \to NaC{l_{(aq)}} + {H_2}{O_{(l)}}$
A solution of a substance $‘X’$ is used for whitewashing.
$(i)$ Name the substance $‘X’$ and write its formula.
$(ii)$ Write the reaction of the substance $‘X’$ named in $(i)$ above with water.
Explain the "Oxidation'' in terms of gain or loss of oxygen with two examples.
What is the difference between displacement and double displacement reactions ? Write equations for these reactions.
Why should a magnesium ribbon be cleaned before burning in air ?
What does one mean by exothermic and endothermic reactions ? Give examples.