Chemical Equilibrium Questions

Phosphorus pentachloride dissociates as follows, in a closed reaction vessel, ${\text{PCl}}_5(g)\rightleftharpoons {\text{PCl}}_3(g)+{\text{Cl}}_2(g)$. If total pressure at equilibrium of the reaction mixture is $P$ and degree of dissociation of ${\text{PCl}}_5$ is $x$, the partial pressure of ${\text{PCl}}_3$ will be:

The equilibrium constant for the reaction ${\text{SO}}_3(g)\rightleftharpoons {\text{SO}}_2(g)+\frac{1}{2}{\text{O}}_2(g)$ is $K_c=4.9\times 10^{-2}$. The value of $K_c$ for the reaction $2{\text{SO}}_2(g)+{\text{O}}_2(g)\rightleftharpoons 2{\text{SO}}_3(g)$ will be: