Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?

(N/A) The molar concentration of a pure solid or liquid is constant,meaning it is independent of the amount present. For a substance '$X$',the values $[X_{(s)}]$ and $[X_{(l)}]$ remain constant regardless of the quantity taken.
$\therefore \text{Molarity} = \frac{\text{Number of moles}}{\text{Volume}} = \frac{\text{Mass} / \text{Molar mass}}{\text{Volume}} = \frac{\text{Density}}{\text{Molar mass}}$
Since density and molar mass are constant for a pure substance at a given temperature,the concentration is constant.
Because these values are constant,they are incorporated into the equilibrium constant ($K_c$ or $K_p$). Thus,they are omitted from the expression.
Example: $CaCO_{3(s)} \rightleftharpoons CaO_{(s)} + CO_{2(g)}$
The expression is $K_c = [CO_{2}]$.
Here,$[CaCO_{3(s)}]$ and $[CaO_{(s)}]$ are treated as $1$.