Question

"Suvarnabhasm", an ayurvedic drug, is found to contain $400$ ppm of colloidal gold. Mass % of gold (atomic mass of Au $=197$ ) will be :

• A. $0.040$
• B. $7.88$
• C. $0.0788$
• D. $4\times {10}^{-4}$%

Answer 1

The correct option is A $0.040$

Mass % of gold means amount of gold present in $100$ g.
As it is given that, in ${10}^6$ g drug, gold present is $400$ g, so in $100$ g drug, gold is $\frac{400\times 100}{{10}^6}=0.040$ % of the compound.