Answers ACE 2025-26 Physical Science B - Schell Unit Test — Unit testQuestion 14

14

QuizMultiple Choice

Unit Test — Unit test

Question 14 • ACE 2025-26 Physical Science B - Schell

Which describes radioactive decay of a substance?

Answer

A

More of the radioactivity is lost during the first half-life than in later half-lives.

B

More of the radioactivity is lost during the fourth half-life than in the first half-life.

C

Isotopes are the most stable during the first half-life.

D

Isotopes are the least stable during the later half-lives.

Explanation

A half-life is the time it takes for half of the remaining radioactive substance to decay. For example, starting with 100 units, 50 decay in the first half-life; in the next half-life, only 25 of the remaining 50 decay. So more radioactivity is lost during the first half-life than during later half-lives, as choice A states.

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