(A) Adsorption is accompained by decrease in enthalpy as well as in entropy of the system $\Delta G=\Delta H-T \Delta S$ and adsorption is an exothermic process [ thus has $\Delta H=(-)$ ve, i.e. decreases] and randomness, i.e. ( $\Delta$ S) also decreases because after adsorption free movement is restricted, but to make the $\Delta G(-)$ ve, $\Delta H>T$. $\Delta S$. Hence, the statement (A) is correct.
(B) Gases, which can react strongly with adsorbent show chemisorption as they form chemical bonds with the adsorbent. Hence, the statement (c) is also correct.
(C) When the value of slope of the Freundlich isotherm is non-zero, adsorption of a gas depends on pressure over it, till the adsorption is possible. According to Freundlich isotherm equation :
$\frac{x}{m}=k \cdot p^{1 / n}$
where,
$x=$ mass of gas adsorbed,
$m=$ mass of adsorbent,
$p=$ pressure,
$k=$ constant,
$n=$ integer number,
Hence, statement (C) is not correct.
(D) Gold number is defined as, "The number of milligrams of a hydropbilic colloid that will just prevent the precipitation of $10 \mathrm{~mL}$ of a pold sol on the addition of $1 \mathrm{~mL}$ of $10 \%$ sodium chloride solution". Gold number for patalo starch is 20
Hence, statements (C) and (D) are not correct and therefore (d) is the correct option.