The given question is incomplete. The complete question is :
Carbon tetrachloride can be produced by the following reaction:

Suppose 1.20 mol
of and 3.60 mol of
were placed in a 1.00-L flask at an unknown temperature. After equilibrium has been achieved, the mixture contains 0.72 mol of
. Calculate equilibrium constant at the unknown temperature.
Answer: The equilibrium constant at unknown temperature is 0.36
Explanation:
Moles of
= 1.20 mole
Moles of
= 3.60 mole
Volume of solution = 1.00 L
Initial concentration of
= 
Initial concentration of
= 
The given balanced equilibrium reaction is,

Initial conc. 1.20 M 3.60 M 0 0
At eqm. conc. (1.20-x) M (3.60-3x) M (x) M (x) M
The expression for equilibrium constant for this reaction will be,
![K_c=\frac{[S_2Cl_2]\times [CCl_4]}{[Cl_2]^3[CS_2]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BS_2Cl_2%5D%5Ctimes%20%5BCCl_4%5D%7D%7B%5BCl_2%5D%5E3%5BCS_2%5D%7D)
Now put all the given values in this expression, we get :

Given :Equilibrium concentration of
, x = 


Thus equilibrium constant at unknown temperature is 0.36