What is the concentration of Tc-99m if 1.2 curies are eluted in a 5.7 ml volume?

To determine the concentration of Tc-99m in millicuries per milliliter (mCi/ml), you need to convert the amount of activity from curies to millicuries, and then divide that value by the volume in milliliters.

Tc-99m has an activity of 1.2 curies. Since there are 1,000 millicuries in 1 curie, we convert the activity:

1.2 curies = 1.2 x 1,000 mCi = 1,200 mCi.

Next, the concentration is calculated by dividing the total activity by the volume:

Concentration (mCi/ml) = Total Activity (mCi) / Volume (ml)

Concentration (mCi/ml) = 1,200 mCi / 5.7 ml ≈ 210.53 mCi/ml.

When rounded, this concentration is approximately 210 mCi/ml, which corresponds to the first choice. This shows that the concentration of Tc-99m is effectively 210 mCi/ml, making it the correct answer.