Answer :
This question is about the concept of radioactive decay, which is a common topic in high school chemistry.
When a radioactive substance decays, it follows a pattern known as exponential decay, where the substance decreases over time at a rate proportional to its current value. One key aspect of this process is the concept of 'half-life,' which is the time required for half of the atoms in a radioactive substance to decay.
Let's analyze each statement:
Statement A: 'After 5.00 h, half of the atoms will have decayed, and the remainder will decay in the next 5.00 h.'
- This statement is incorrect. After 5.00 hours, half of the atoms will have decayed, which is correct. However, it does not mean that all of the remaining atoms will decay in the next 5.00 hours. Instead, only half of the remaining amount will decay in the subsequent 5.00 hours.
Statement B: 'After 5.00 h, half of the atoms will have decayed, and half of the remainder will decay in the next 5.00 h.'
- This statement is correct. After the initial 5.00 hour period, 50% of the original atoms would have decayed. In the next 5.00 hour period, half of the remaining atoms from the first period will decay, following the principle of half-life.
Statement C: 'After 5.00 h, the mass in the beaker will be only half its original value.'
- This statement is correct, assuming the substance is purely radioactive with no other non-decaying materials present. After one half-life, half of the atoms, which directly relates to the mass if the only constituent decays, will have decayed.
So, the correct options from the choices given are B, C.
