Which of the following statements is incorrect?

An artificial pacemaker is implanted subcutaneously and connected to the heart in patients:

Justify that the following reactions are redox reactions:
$a$. $CuO_{(s)} + H_{2(g)} \rightarrow Cu_{(s)} + H_2O_{(g)}$
$b$. $Fe_2O_{3(s)} + 3CO_{(g)} \rightarrow 2Fe_{(s)} + 3CO_{2(g)}$
$c$. $4BCl_{3(g)} + 3LiAlH_{4(s)} \rightarrow 2B_2H_{6(g)} + 3LiCl_{(s)} + 3AlCl_{3(s)}$
$d$. $2K_{(s)} + F_{2(g)} \rightarrow 2K^{+}F^{-}_{(s)}$
$e$. $4NH_{3(g)} + 5O_{2(g)} \rightarrow 4NO_{(g)} + 6H_2O_{(g)}$

Extraction of zinc from zinc blende is achieved by

Five masses,each of $2 \, kg$,are placed on a horizontal circular disc that can rotate about a vertical axis passing through its centre. All the masses are equidistant from the axis at a distance of $10 \, cm$. The moment of inertia of the whole system (in $g \cdot cm^2$) is (Assume the disc has negligible mass).