Assertion (A): The electron will be ejected from a hydrogen atom when electron beam of kinetic energy \(10.6\text{ eV}\) falls on it.
Reason (R): The difference between \(n_1\) and \(n_2\) is \(10.2\text{ eV}\).
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Ionization energy of H atom is \(13.6\text{ eV}\). \(10.6\text{ eV}\). is insufficient to ionize. \(\Delta E_{2-1} = 10.2\text{ eV}\). If 'ejected' means excited to \(n=2\), then (A) is true. (R) is true and explains the excitation.
Assertion (A): It is easier to release an orbital electron, but quite difficult to release a nucleon.
Reason (R): An electron is much lighter than a nucleon.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Electron binding energies are in eV, nucleon binding energies in MeV, so (A) is true. Electron mass \(9.11 \times 10^{-31}\text{ kg}\) is much less than nucleon mass \(1.67 \times 10^{-27}\text{ kg}\), so (R) is true. The difference in ease of release is due to different fundamental forces, not primarily mass. So (R) does not explain (A).
Assertion (A): In solid each electron will have a different energy level.
Reason (R): In solid crystal each electron has a unique position and no two electrons see exactly the same pattern of surrounding charges.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Due to the Pauli exclusion principle, no two electrons can occupy the same quantum state. In a solid, each electron experiences a unique electrostatic environment. Thus, Assertion (A) is true, and Reason (R) provides the correct explanation for it.