Question

The half life of a radioisotope is _____________

(a) half the time taken for complete decay

(b) half the time taken for half the decay

(c) time taken for complete decay

(d) time taken for half the decay

I got this question by my school teacher while I was bunking the class.

My question is taken from Techniques in section Techniques in Cell Biology of Cell Biology

Answer 1

The half-life of a radioisotope is defined as the time required for half of the radioactive nuclei in a sample to decay. This means that, after one half-life, only half of the original amount of the radioisotope remains.

Let’s review the options:

• (a) Half the time taken for complete decay: This is incorrect, as half-life does not represent a fraction of the total time for complete decay.

• (b) Half the time taken for half the decay: This phrasing is incorrect; it misinterprets the concept of half-life.

• (c) Time taken for complete decay: Radioactive decay is a probabilistic process, so it technically never "completes" entirely; there will always be some remaining nuclei.

• (d) Time taken for half the decay: This is correct, as half-life specifically refers to the time required for half of the substance to decay.

Correct Answer: (d) Time taken for half the decay