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

Options

A. `0.040 %`
B. `7.88 %`
C. `0.0788 %`
D. `4xx10^(-4) %`

Explanation

To find the mass percent of gold in "Suvarnabhasm" which contains 400 ppm of colloidal gold, we can follow these steps:

### Step 1: Understand the definition of ppm
PPM stands for "parts per million." It indicates how many parts of a substance are present in one million parts of a solution or mixture. In this case, 400 ppm means there are 400 grams of gold in 1,000,000 grams of the drug.

### Step 2: Convert ppm to mass percent
To find the mass percent of gold in the drug, we can use the following formula:

\[ \text{Mass percent of gold} = \left( \frac{\text{mass of gold}}{\text{mass of drug}} \right) \times 100 \]

Given that there are 400 grams of gold in 1,000,000 grams of the drug, we can calculate the mass percent of gold in 100 grams of the drug.

### Step 3: Calculate the mass of gold in 100 grams of the drug
We can set up a proportion to find out how much gold is present in 100 grams of the drug:

\[ \text{Mass of gold in 100 grams} = \frac{400 \, \text{grams of gold}}{1,000,000 \, \text{grams of drug}} \times 100 \, \text{grams of drug} \]

Calculating this gives:

\[ \text{Mass of gold in 100 grams} = \frac{400 \times 100}{1,000,000} = \frac{40000}{1000000} = 0.04 \, \text{grams} \]

### Step 4: Calculate the mass percent
Now, we can substitute this value back into the mass percent formula:

\[ \text{Mass percent of gold} = \left( \frac{0.04 \, \text{grams of gold}}{100 \, \text{grams of drug}} \right) \times 100 \]

Calculating this gives:

\[ \text{Mass percent of gold} = 0.04 \% \]

### Final Answer
The mass percent of gold in "Suvarnabhasm" is **0.04%**.

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