' X ' is a protecting colloid. The following data is obtained for preventing the coagulation of 10 mL of…
' X ' is a protecting colloid. The following data is obtained for preventing the coagulation of 10 mL of gold sol to which 1 mL of $10 \% \mathrm{NaCl}$ is added. What is the gold number of ' $X$ '?
$24$
$26$
$27$
$25$
Solution
Gold number is the number of milligrams of the protective colloid which prevent the coagulation.
When 1 ml of $10 \%$ solution of sodium chloride is added then coagulation happens X is the protecting colloid. Smaller the gold number of protecting colloid. Greater is the protecting power. So the gold number of X is 25 .
