For the reaction $PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$,what is the relationship between $K_p$ and $K_c$?

For the given equilibrium reaction,$2 A(g) \rightleftharpoons 2 B(g) + C(g)$,the equilibrium constant $(K_c)$ at $1000 \ K$ is $4 \times 10^{-4}$. Calculate $K_p$ for the reaction at $800 \ K$ temperature.

For the reactions:
$2NO + O_2 \rightleftharpoons 2NO_2$; $K_1$
$4NO + 2Cl_2 \rightleftharpoons 4NOCl$; $K_2$
$NO_2 + \frac{1}{2}Cl_2 \rightleftharpoons NOCl + \frac{1}{2}O_2$; $K_3$
Where $K_1, K_2, K_3$ are equilibrium constants,then $K_3^2$ is equal to:

Given $K_p$ for the reaction $\frac{1}{2} C_{(g)} \rightleftharpoons \frac{1}{2} A_{(g)} + \frac{1}{2} B_{(g)}$ at a fixed temperature is $0.25 \ atm$. Find the $K_p$ for the reaction $A_{(g)} + B_{(g)} \rightleftharpoons C_{(g)}$ at the same temperature.

For the reaction $MgCO_{3(s)} \rightleftharpoons MgO_{(s)} + CO_{2(g)}$,the value of $K_p$ is:

$NH_4COONH_{2_{(s)}} \rightleftharpoons 2NH_{3_{(g)}} + CO_{2_{(g)}}$. If the equilibrium pressure is $3 \, atm$ for the above reaction,the $K_p$ for the reaction is: