In the figure shown below reactant A (represented by square) is in equilibrium with product B (represented by circle). The equilibrium constant is (approx):

Step 1: Count the Chemical Species at Equilibrium

By carefully counting the shapes shown in the given system snapshot, we find:

• Number of Reactant A molecules (Squares): 5
• Number of Product B molecules (Circles): 10

Step 2: Calculate the Equilibrium Constant ($$K$$)

The equilibrium constant expression for a simple $$A \rightleftharpoons B$$ reaction is given by the ratio of the concentration (or count) of products to reactants:

$$K = \frac{[\text{Products}]}{[\text{Reactants}]} = \frac{[\text{B}]}{[\text{A}]}$$

Substituting our counts into the formula:

$$K = \frac{10}{5} = 2$$

Conclusion:

The system contains twice as many product molecules as reactant molecules at equilibrium, yielding an equilibrium constant of 2.

Answer: Option D — 2