Question

‘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% NaCl is added. What is the gold number of ‘X’?

• A. \( 24 \)
• B. \( 26 \)
• C. \( 27 \)
• D. \( 25 \)

Hint:

- Gold number is the minimum mass of a protective colloid (in mg) required to prevent coagulation of 10 mL of gold sol by 1 mL of 10\% NaCl. - Lower gold number = Better protective power of the colloid.

Answer 1

The Correct Option is D

The gold number is the minimum weight (in milligrams) of a protective colloid required to prevent the coagulation of 10 mL of a standard gold sol when 1 mL of a 10% NaCl solution is added.

From the table, we can see that coagulation is prevented when 25 mg, 26 mg, and 27 mg of X are added. The gold number is the minimum amount required, which is 25 mg.

Therefore, the gold number of X is 25.