Question

The activity of a radioactive sample is measured as \( N_0 \) counts per minute at \( t = 0 \) and \( N \) counts per minute at \( t = 5 \) min. The time, in minutes, at which the activity reduces to half its value is?

• A. \( \log_2 5 \)
• B. \( \log_2 2 \)
• C. \( 5 \log_2 2 \)
• D. \( 5 \log_2 5 \)

Hint:

The time for a radioactive sample to decay to half its activity is its half-life, which can be calculated from the decay constant.

Answer 1

The Correct Option is C

The time at which the activity halves is determined by the half-life of the substance. Using the decay law, the time can be calculated based on the logarithmic relationship between the initial and reduced activity.