Radiology – MCQ 27 – Rate of decay

At t=0 there are 6 x 10^23 radioactive atoms of a substance, which decay with a disintegration constant equal to 0.01/sec. What would be the initial decay rate?
A. 6 X 10^23
a. 6 X 10^22
c. 6 X 10^21
d. 6 X 10^20

Correct answer : c. 6 X 10^21

Rate of decay = Disintegration constant X Number of radioactive atoms
= 0.01 X 6 x 10^23
= 6 X 10^21