Question

Hydrogen will not reduce?

• A. $\mathrm{CuO}$
• B. ${\mathrm{Fe}}_3{\mathrm{O}}_4(\mathrm{Ferric}\mathrm{oxide})$
• C. ${\mathrm{SnO}}_2$
• D. ${\mathrm{Al}}_2{\mathrm{O}}_3$

Answer 1

The correct option is D

${\mathrm{Al}}_2{\mathrm{O}}_3$

The explanation for the correct option:

Option (D):

• Hydrogen can only reduce substances that are below it in the oxidizer table.
• Aluminium is said to be more reactive than hydrogen.
• So hydrogen can’t displace aluminium from ${\mathrm{Al}}_2{\mathrm{O}}_3$.

The explanation for incorrect options:

Option (A):

• The copper is below the hydrogen and they are less reactive.
• Hence, hydrogen can reduce copper easily from $\mathrm{CuO}$.

Option (B):

• $\mathrm{Fe}$ lies above the hydrogen in the electrochemical series and hence is more reactive.
• But, in the case of ${\mathrm{Fe}}_3{\mathrm{O}}_4(\mathrm{Ferric}\mathrm{oxide})$,$$Fe$$ gets reduced by Hydrogen from$\mathrm{F}{\mathrm{e}}^{3+}$to $$F{e}^{2+}$$, which is the more stable form of Iron.
• Hence, Iron can be reduced by hydrogen from ${\mathrm{Fe}}_3{\mathrm{O}}_4(\mathrm{Ferric}\mathrm{oxide})$.

Option (C):

• $\mathrm{Sn}$ lies above the hydrogen in the electrochemical series and hence is more reactive.
• But, in case of ${\mathrm{SnO}}_2$,$\mathrm{Sn}$ gets reduced by Hydrogen, from$S{n}^{4+}$to $$S{n}^{2+}$$,which is the more stable form of $\mathrm{Sn}$.
• Thus it can be reduced by hydrogen from ${\mathrm{SnO}}_2$.

Therefore the correct option is (D). Hydrogen will not reduce ${\mathrm{Al}}_2{\mathrm{O}}_3$.