Concepts Of Physics MCQ Edition [Volume 2]PhysicsThe Nucleus
During a single average-life,
Options
- Amore than half of the active nuclei decay
- Bhalf of the active nuclei decay
- Call of the nuclei decay
- Dfewer than half of the active nuclei decay
Correct answer
A. more than half of the active nuclei decay
Step-by-step solution
The number of active nuclei remaining after time t is given by the radioactive decay law: N = N₀ e^ - t The average life (or mean life) of a radioactive substance is = 1 . Substituting t = = 1 in the decay equation: N = N₀ e^ - ( 1 ) = N₀ e⁻¹ = N₀ e Since e 2.718 , the number of remaining active nuclei is: N = N₀ 2.718 0.368 N₀ The number of nuclei that have decayed during this time is: N_ decayed = N₀ - N = N₀ - 0.368 N₀ = 0.632 N₀ This means approximately 63.2 % of the initial active nuclei decay during one avera