Question

The Rubin number which was proposed by Ostwald as an alternative to the Gold number in order to measure the protective efficiency of a lyophillic colloid may be defined as the

• A. mass in milligrams of a colloid per 100 c.c. of solution which just prevents the colour change Of standard sol of dye Congo-Rubin from red to violet when 0.16 g eq. KCl is added to it
• B. mass in grams of a colloid per 100 c.c. of solution which just prevents the colour change of standard sol of dye Congo-Rubin from red to violet when 0.1 M KCl is added to it
• C. mass in grams of a colloid per 100 c.c. of solution which just prevents the colour change of standard sol of dye Congo-Rubin from red to violet when 0.2 M KCl is added to it
• D. mass in grams of a colloid per 100 c.c. of solution which just prevents the colour change of standard sol of dye Congo-Rubin from red to violet when 1M KCl is added to it

Answer 1

Answer: (A)

Correct answer is (a) mass in milligrams of a colloid per 100 c.c. of solution which just prevents the colour change Of standard sol of dye Congo-Rubin from red to violet when 0.16 g eq. KCl is added to it