What is the half-life of a radioactive substance?

Question

Question

Answer 1

Correct Answer: The time it takes for its activity to reduce by half

Rationale:

The half-life of a radioactive substance is the time required for half of the radioactive atoms in a sample to decay. This means that the activity, or the number of disintegrations per unit time, of the substance reduces by half during this period.
The concept of half-life is fundamental in understanding the decay process of radioactive materials, and it is crucial for applications in nuclear medicine, radiometric dating, and nuclear power generation.

Explanation of Other Options:

The time it takes for its mass to reduce by half

Rationale: This statement is incorrect because the mass of a radioactive substance does not reduce by half during its half-life. Instead, the reduction occurs in the number of radioactive atoms, not the mass itself.

The time it takes for the radiation to become harmless

Rationale: This statement is incorrect because the half-life of a radioactive substance does not directly relate to the time it takes for radiation to become harmless. The danger posed by radiation depends on several factors, including the type of radiation and the total amount of radioactive material present.

The time it takes for its temperature to decrease by half

Rationale: This statement is incorrect because the half-life of a radioactive substance is not related to its temperature. The concept of half-life is specific to radioactive decay and does not pertain to thermal properties.

Conclusion:

The half-life of a radioactive substance is an essential concept in nuclear physics and various practical applications. It specifically refers to the time required for half of the radioactive atoms to decay, thereby reducing the activity of the substance by half. This understanding helps in predicting the behavior of radioactive materials over time and their safe handling.