A 0.20-mL sample of a solution containing that produces 3.7 * 10³ cps is injected into the bloodstream of an animal. After circulatory equilibrium has been established, a 0.20-mL sample of blood is found to have an activity of 20 cps. Calculate the blood volume of the animal. A) 18 mL B) 180 mL C) 11 mL D) 37 mL E) none of these

Question

Quizplus · Accepted Answer

The initial activity of the injected solution is 3.7 x 10^10 cps in a volume of 0.20 mL. Let x be the blood volume of the animal in mL. At equilibrium, the amount of solute in the bloodstream is the same as the amount of solute in the injected solution:

(11 eaaf8d_c1b5_1123_892c_9d3c118fb7ee_TB6420_11) x (0.20 mL) = (11 eaaf8d_c1b5_1123_892c_9d3c118fb7ee_TB6420_11) x (x mL)

Solving for x, we get:

x = (0.20 mL) / (20 cps / 3.7 x 10^10 cps/mL) = 37 mL

Therefore, the blood volume of the animal is 37 mL, which is answer choice D.

A 020-ML Sample of a Solution Containing That Produces 3