Question

The coagulation of `100 mL` of a colloidal solution of gold is completely prevented by the addition of `0.030 g` of it before adding `1 mL` of `10% NaCl` solution. Find out the gold number of starch?
A. 4
B. 8
C. 3
D. 9

Answer 1

Correct Answer - A
Haemoglobin added to `100mL` of gold sol to prevent coagulation by `1mL` of `10%NaCl` sol `=0.03g=30mg` haemoglobin required to be added to `10%NaCl` sol `=3mg` .
Therefore, gold number of haemoglobin `=3` .