The Isotope Has a Half-Life of 7

question 11

Multiple Choice

The isotope has a half-life of 7.5 seconds. If a sample contains 144 atoms of approximately how many such atoms were there present 30 seconds earlier?

• A) 576
• B) 1152
• C) 2304
• D) 4320
• E) 4.30 × 10⁸

---

Definitions:

Self-Discrepancy Theory

The theory that people feel anxiety when they fall short of how they ought to be but feel sad when they fall short of how they ideally want to be.

Ideal Self

A person's conception of how they would like to be, embodying their goals, aspirations, and unique potential.

Vision

The ability to think about or plan the future with imagination or wisdom; often refers to the capability to see with the eyes.

Mental Fatigue

A state of tiredness or exhaustion that originates from prolonged cognitive activity, reducing an individual's capacity for mental work.