c
\(2 \mathrm{NO}_{(\mathrm{g})} \rightleftharpoons \mathrm{N}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}\)

\(\mathrm{K}_{\mathrm{c}} \)\( =\frac{\left[\mathrm{N}_2\right]\left[\mathrm{O}_2\right]}{[\mathrm{NO}]^2} \)

\( =\frac{3 \times 10^{-3} \times 4.2 \times 10^{-3}}{2.8 \times 10^{-3} \times 2.8 \times 10^{-3}} \)

\( =1.607\)

\(2 \mathrm{NO}_{(\mathrm{g})} \rightleftharpoons \mathrm{N}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \)

\(\mathrm{t}=0 \)

\(0.1 \quad 0 \quad 0 \)

\(0.1-0.1 \alpha \quad 0.05 \alpha \quad 0.05 \alpha \)

\(\mathrm{K}_{\mathrm{c}}=\frac{0.05 \alpha \times 0.05 \alpha}{(0.1-0.1 \alpha)^2} \)

\(\mathrm{~K}_{\mathrm{c}}=\frac{0.05 \alpha \times 0.05 \alpha}{0.01(1-\alpha)^2} \)

\(1.607=\frac{(0.05)^2 \alpha^2}{0.01(1-\alpha)^2} \)

\(\frac{\alpha^2}{(1-\alpha)^2}=\frac{1.607 \times(0.1)^2}{(0.05)^2} \)

\(\frac{\alpha}{1-\alpha}=\frac{1.27 \times 0.1}{0.05} \)

\(\frac{\alpha}{1-\alpha}=2.54 \)

\(\alpha=2.54-2.54 \alpha \)

\(3.54 \alpha=2.54 \)

\(\alpha=\frac{2.54}{3.54}=0.717\)