Question

Gold numbers of protective colloids $\left(A\right),\left(B\right),\left(C\right),$ and $\left(D\right)$ are $0.50,0.01,0.10$ and $0.005$ respectively. The correct order of their protective powers is:

• A. $\left(A\right)<\left(C\right)<\left(B\right)<\left(D\right)$
• B. $\left(B\right)<\left(D\right)<\left(A\right)<\left(C\right)$
• C. $\left(D\right)<\left(A\right)<\left(C\right)<\left(B\right)$
• D. $\left(C\right)<\left(B\right)<\left(D\right)<\left(A\right)$

Answer 1

The correct option is A $\left(A\right)<\left(C\right)<\left(B\right)<\left(D\right)$

Gold number is defined as the number of milligrams of the protective colloid that will just prevent the coagulation of $10$ ml gold sol on the addition of $1$ ml of $10$ percent sodium chloride solution.

The decreasing order of the values of the gold numbers of protective colloids is

$0.50\left(A\right)>0.10\left(C\right)>0.01\left(B\right)>0.005\left(D\right)$.

Lesser the value of the gold number of a protective colloid, better is its protective power. Hence, the correct order of the protective powers is

$\left(A\right)<\left(C\right)<\left(B\right)<\left(D\right)$.