Question

A radioactive substance exhibits the following pattern of decay.

- Amount of Material (g): 100, 75, 50, 25, 12.5
- Years: 0, 1, 2, 3, 4
What is the half-life of this substance?
- A) 1 year
- B) 2 years
- C) 3 years
- D) 4 years

Answer 1

The half-life of the radioactive substance is 2 years, as the amount of the substance halves from 100g to 50g after 2 years.

Step-by-step explanation:

The half-life of a radioactive substance is the time it takes for half of the initial amount of the substance to radioactively decay. In the case of the substance in question, the pattern of decay is 100g at year 0, 50g at year 2, indicating that half of the substance has decayed after 2 years. Thus, this is the half-life of the substance.

Since the half-life is a consistent measure, after one more half-life (another 2 years), the amount would be halved again, resulting in 25g at year 4. By observing the pattern of decay given: 100g, 75g, 50g, 25g, and 12.5g over the years 0, 1, 2, 3, and 4 respectively, we can see that the material halves every 2 years. Therefore, the correct answer to the student's question is B) 2 years.