On addition of one ml solution of 10%NaCl to 10 ml gold sol in the presence of 0.25 gm of starch, the coagulation is just prevented. Starch has the following gold number

A
0.025
B
0.25
C
0.5
D
250

Solution:

By definition gold number of starch is the amount of starch in mg added to 10 ml standard gold sol which prevents the coagulation of gold on adding 1 ml of 10% NaCl solution. So the amount of starch is 0.25 g = 250 mg. Hence gold number is 250.

On addition of one ml solution of $10 % N a C l$ to $10 m l$ gold sol in the presence of 0.25 gm of starch, the coagulation is just prevented. Starch has the following gold number

Solution:

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