Question

${10}^{-4}$ g of gelatin is required to be added to 100 $c{m}^3$ of a standard gold solution to just prevent its precipitation by addition of 1 $c{m}^3$ of 10% NaCl solution to it. Hence the gold number of gelatin is

• A. 10
• B. 1
• C. 0.1
• D. 0.01

Answer 1

The correct option is D 0.01

${10}^{-4}$ g = 0.1 mg
100 $c{m}^3$ of gold sol require 0.1 mg
∴ 10 $c{m}^3$ of gold sol will required 0.01 mg
Hence, gold number = 0.01