# Gold numbers of protective colloids A ,B ,C and D are 0.50 , 0.01 , 0,05 and 0.005 respectively , the correct order of their protective powers is

$(a)\;A < C < B < D\qquad(b)\;B < D < A < C\qquad(c)\;D < A < C < B\qquad(d)\;C < B < D < A$

Answer : $A < C < B < D$
Explanation :
Smaller the gold number , greater is the protective power . Thus protective power . Thus protective power of A , B ,C and D are in the order .
$D(0.005) > B(0.01) > C (0.05) > A (0.50)\;$ or
$A < C < B < D \;$ in order of protective powers .