Identify the substances that are oxidised and the substances that are reduced in the following reactions.
$(i)$ $4 Na ( s )+ O _{2}( g ) \rightarrow 2 Na _{2} O ( s )$
$(ii)$ $CuO ( s )+ H _{2}( g ) \rightarrow Cu ( s )+ H _{2} O ( l )$
$(i)$ Sodium $(Na)$ is oxidised as it gains oxygen and oxygen gets reduced.
$(ii)$ Copper oxide $(CuO)$ is reduced to copper $(Cu)$ while hydrogen $(H_2)$ gets oxidised to water $(H_2O)$.
Explain the ''Corrosion'' terms with one example.
Why is respiration considered an exothermic reaction ? Explain.
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.
What is the difference between displacement and double displacement reactions ? Write equations for these reactions.
Write the balanced chemical equations for the following reactions.
$(a)$ Calcium hydroxide $+$ Carbon dioxide $\rightarrow$ Calcium carbonate $+$ Water
$(b)$ Zinc $+$ Silver nitrate $\rightarrow$ zinc nitrate $+$ Silver
$(c)$ Aluminium $+$ Copper chloride $\rightarrow$ Aluminium chloride $+$ Copper
$(d)$ Barium chloride$+$ Potassium sulphate $\rightarrow$ Barium sulphate $+$ Potassium chloride