Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
$(a)$ Thermal decomposition :
$\underset{Ferrous\,\,sulphate}{\mathop{2FeS{{O}_{4}}}}\,\,\xrightarrow{\Delta }$$\mathop {F{e_2}{O_{3(s)}}}\limits_{Ferric\,\,\,oxide} \, + \mathop {\,S{O_{2(g)}}}\limits_{Sulphur{\text{ }}dioxide\;} \, + \mathop {\,S{O_{3(g)}}}\limits_{Sulphur{\text{ }}trioxide} $
$(b)$ Decomposition by light :
$2AgC{l_{(s)}}\;\xrightarrow{{{\text{ Light }}}}\mathop {2A{g_{(s)}}}\limits_{Silver} + \mathop {C{l_{2(g)}}}\limits_{Chlorine} $
$(c)$ Decomposition by electricity :
$\mathop {2A{l_2}{O_{3(aq)}}}\limits_{Aluminium{\text{ }}oxide} \xrightarrow{{{\text{ Electricity }}}}\mathop {\;{\kern 1pt} 4A{l_{(s)}}}\limits_{Aluminium} + \mathop {3{O_{2(g)}}}\limits_{Oxygen} $
Explain the ''Corrosion'' terms with one example.
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.
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.
Identify the substances that are oxidised and the substances that are reduced in the following reactions.
$(i)$ $4 Na ( s )+ O _{2}( g ) \rightarrow 2 Na _{2} O ( s )$
$(ii)$ $CuO ( s )+ H _{2}( g ) \rightarrow Cu ( s )+ H _{2} O ( l )$
Explain the ''Rancidity'' terms with one example.