On addition of 0.8 mL of solution of 10% NaCl to 30 mL of red gold sol in presence of 0.03 g of starch, the coagulation is just prevented. The gold number of starch is

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The coagulation of 10 cm3 of Gold sol by 1 ml 10% NaCl solution is completely prevented by addition of 0.25 g of starch to it. The gold number of starch is:

The correct option is D 250Gold number is the weight of a protective colloid in milligrams, which prevents the coagulation of 10 mL of gold sol. Gold number of starch is =0.25×1000=250 mg

The coagulation of $10 {cm}^{3}$ of Gold sol by $1 ml 10 % N a C l$ solution is completely prevented by addition of $0.25 g$ of starch to it. The gold number of starch is:

The correct option is D $250$
Gold number is the weight of a protective colloid in milligrams, which prevents the coagulation of 10 mL of gold sol.
Gold number of starch is $= 0.25 \times 1000 = 250 mg$