Question

Select the correct statement:
(A) The same amount will decay in every half-life
(B) Amount decayed in first half-life is maximum
(C) Amount decayed in first half-life is minimum
(D) Amount decayed in a half-life depends on the nature of the element

Answer 1

Half-Life Period: It is defined as the time required for a certain amount of a given matter to fall to half of its given value.
In simple words, for an atomic nucleus (or for an atom) half-life period is the time required to decay the amount of the atom to half of the original amount taken.

Complete step by step solution:

The amount decayed in any half-life is equal to half of the initial amount.
The amount of substance is maximum originally.
Therefore, the amount decayed in the first half is maximum.
Hence, the correct option is B.
The decay half-life of radioactive material can be changed. It is impossible to predict when an individual radioactive atom will decay.
The law of radioactive decay states that the rate of decay of nuclei present in an atom is directly proportional to the concentration of nuclei present (in other words directly proportional to the no of nuclei)
The half-life of a particular type of atom does not describe the exact amount of time that every single atom experiences before decaying.

Note: The possibility to make a mistake is that you may choose option C. As the substance is decaying the half-life may decrease but in the first half the amount of decaying is maximum.