Due to absence of d-orbitals, Al does not show inert pair effect. Therefore, its most stable oxidation state is +3. Thus, AlCl₃ is much more stable AlCl. Further, in the solid or the vapour state, AlCl_{3 is} covalent in nature but in aqueous solutions, it ionises to form Al³⁺(aq) and Cl^-(aq)ions.

Due to inert pair effect, indium exists in both +1 and +3 oxidation states, out of which +3 oxidation state is more than +1 oxidation state. In other words, InCl₃ is more stable than InCl. Being unstable, InCl undergoes disproportionation reaction.
\(3InCl(aq)\rightarrow 2In(s)+In^{ 3+ }(aq)+3Cl^{ - }(aq)\)

Producer gas is a mixture of CO and N₂, therefore, the tetravalent element is carbon and its monoxide and dioxide are CO and CO₂ respectively.
\(2C(s)+\underbrace { O_{ 2 }(s)+4N_{ 2 }(g) }_{ Air } \overset { 1273k }{ \rightarrow } \underbrace { 2CO(g)+4N_{ 2 }(g) }_{ Producer \ gas } \)
The carbon monoxide is a strong reducing agent and reduces ferric oxide to iron.
\(Fe_{ 2 }O_{ 3 }(s)+3CO(g)\overset { \Delta }{ \rightarrow } 2Fe(s)+3CO_{ 2 }(g)\)

\(Na_{ 2 }B_{ 4 }{ O }_{ 7 }+2HCl+5{ H }_{ 2 }O \ \rightarrow \ 2NaCl+4H_{ 3 }BO_{ 3 }\)
Borax(A)                                               Orthoboric acid(X)
\(H_{ 3 }BO_{ 3 } \ \underrightarrow { \Delta ,370K } \ HBO_{ 2 }+{ H }_{ 2 }O\)
(X)                         Metaboric acid
\(4 \ HBO_{ 2 }\xrightarrow [ \Delta ,>370K ]{ -H_{ 2 }O } [{ H }_{ 2 }B_{ 4 }{ O }_{ 7 }]\underrightarrow { Red \ heat } \ 2{ B }_{ 2 }{ O }_{ 3 }+H_{ 2 }O\)
                             Tetraboric acid            Boron trioxide

\(4BF_{ 3 }+3LiAlH_{ 4 }\rightarrow 2B_{ 2 }H_{ 6 }+3LiF+3AlF_{ 3 }\)
Boron trifluride(Z)           Diborane(X)
\(B_{ 2 }H_{ 6 }+6H_{ 2 }O\rightarrow 2H_{ 3 }BO_{ 3 }+6H_{ 2 }\)
(X)                     Orthoboric acid(Y)
\(B_{ 2 }H_{ 6 }+3O_{ 2 }\underrightarrow { \Delta } B_{ 2 }O_{ 3 }+3{ H }_{ 2 }O\)
(X)