Question
The expression for equilibrium constant, $${K_c}$$ for the following reaction is $$2Cu{\left( {N{O_3}} \right)_{2\left( s \right)}} \rightleftharpoons $$ $$2Cu{O_{\left( s \right)}} + 4N{O_{2\left( g \right)}} + {O_{2\left( g \right)}}$$
A.
$${K_c} = \frac{{{{\left[ {Cu{O_{\left( s \right)}}} \right]}^2}{{\left[ {N{O_{2\left( g \right)}}} \right]}^4}\left[ {{O_{2\left( g \right)}}} \right]}}{{{{\left[ {Cu{{\left( {N{O_3}} \right)}_{2\left( s \right)}}} \right]}^2}}}$$
B.
$${K_c} = \frac{{{{\left[ {N{O_{2\left( g \right)}}} \right]}^4}\left[ {{O_{2\left( g \right)}}} \right]}}{{{{\left[ {Cu{{\left( {N{O_3}} \right)}_{2\left( s \right)}}} \right]}^2}}}$$
C.
$${K_c} = {\left[ {N{O_{2\left( g \right)}}} \right]^4}\left[ {{O_{2\left( g \right)}}} \right]$$
D.
$${K_c} = \frac{{{{\left[ {Cu{O_{\left( s \right)}}} \right]}^2}}}{{{{\left[ {Cu{{\left( {N{O_3}} \right)}_{2\left( s \right)}}} \right]}^2}}}$$
Answer :
$${K_c} = {\left[ {N{O_{2\left( g \right)}}} \right]^4}\left[ {{O_{2\left( g \right)}}} \right]$$
Solution :
$$2Cu{\left( {N{O_3}} \right)_{2\left( s \right)}} \rightleftharpoons $$ $$2Cu{O_{\left( s \right)}} + 4N{O_{2\left( g \right)}} + {O_{2\left( g \right)}}$$
Since conc. of solids is taken as 1, the expression for $${K_c}$$ becomes $${K_c} = {\left[ {N{O_{2\left( g \right)}}} \right]^4}\left[ {{O_{2\left( g \right)}}} \right]$$