# Math

posted by
**Darwin12**
.

In 10 years, 25% of a radioactive substance decays. What is its half-life?

A. 25 years

B. 24 years

C. 20 years

D. 29 years

posted by
**Darwin12**
.

In 10 years, 25% of a radioactive substance decays. What is its half-life?

A. 25 years

B. 24 years

C. 20 years

D. 29 years