Answer:
Option c.
Be careful, because you have wrong compounds
Step-by-step explanation:
Our equilibrium is:
Al(NO₃)₃ + 3NaCl ⇄ 3NaNO₃ + AlCl₃
To determine the Kc, the molar concentrations of the products is multiplied, and they are raised to what the stoichiometry indicates and divided by the products of the reactants, which are also raised according to the stoichiometry. We can see this example
aA + bB ⇄ xC + nD
Kc expression will be: [C]ˣ . [D]ⁿ / [B]ᵇ . [A]ᵃ
If we do not have stoichiometry, you know we have a 1.
The expression for Kc, in the equilibrium proposed is:
Kc = [AlCl₃] . [NaNO₃]³ / [NaCl]³ . [Al(NO₃)₃]