Consider the following system at equilibrium where $H=-18\mathrm{.}8kJ,$ and $K_c=10\mathrm{.}5,$ at $350K.$

$2C{H}_{2}C{l}_2(g)C{H}_4(g)+CC{l}_4(g)$

When $0\mathrm{.}27$ moles of $C{H}_4(g)$ are added to the equilibrium system at constant temperature:

the value of $K_c$

A$.$ increases.

B$.$ decreases.

C$.$ remains the same.

the value of $Q_c$

A$.$ is greater than $K_c.$

B$.$ is equal to $K_c.$

C$.$ is less than $K_c.$

the reaction must:

A$.$ run in the forward direction to restablish equilibrium.

B$.$ run in the reverse direction to restablish equilibrium.

C$.$ remain the same. It is already at equilibrium.

the concentration of $CC{l}_4$ will:

A$.$ increase.

B$.$ decrease.

C$.$ remain the same.