If the potential energy is taken zero at ground state of hydrogen atom in place of infinity then

Options

A. Total energy of atom will get changed
B. Binding energy of hydrogen atom in ground state will remain unchanged
C. Kinetic energy of electron in ground state will get changed
D. Energy of photon generated because of de-excitation of atom from first excited state will remain unchanged

Answer

To solve the problem, we need to analyze the implications of taking the potential energy of the hydrogen atom as zero at the ground state instead of at infinity.

### Step-by-Step Solution:

1. **Understanding the Ground State**:
- The ground state of a hydrogen atom corresponds to the principal quantum number \( n = 1 \). In this state, the electron is in the lowest energy level.

2. **Potential Energy Reference**:
- In quantum mechanics, the potential energy of an electron in a hydrogen atom is typically taken to be zero when the electron is infinitely far from the nucleus. This is the conventional reference point.
- If we redefine the potential energy to be zero at the ground state (when \( n = 1 \)), we need to analyze how this affects the total energy of the system.

3. **Total Energy Calculation**:
- The total energy \( E \) of the hydrogen atom in the ground state can be expressed as:
\[ E = K + V \]
where \( K \) is the kinetic energy and \( V \) is the potential energy.
- In the conventional case, the potential energy at the ground state is negative (since it is bound) and the total energy is also negative.

4. **Change in Total Energy**:
- If we take the potential energy \( V \) to be zero at the ground state, we effectively shift the energy scale. The total energy will now be higher (less negative) compared to the conventional case.
- This means that the total energy of the atom will change when we redefine the potential energy reference point.

5. **Binding Energy**:
- The binding energy of the electron in the atom is defined as the energy required to remove the electron from the atom to infinity (where potential energy is zero).
- Since the binding energy is a measure of how tightly the electron is bound to the nucleus, it remains unchanged regardless of the reference point for potential energy.

6. **Kinetic Energy**:
- The kinetic energy of the electron is related to its motion and is derived from the potential energy. If the potential energy changes, the kinetic energy will also change accordingly.

7. **Photon Energy**:
- The energy of the photon emitted during de-excitation (transition from a higher energy state to a lower energy state) depends on the energy difference between the two states.
- Since the energy levels themselves are shifted uniformly, the energy difference remains the same, and thus the energy of the photon generated during de-excitation remains unchanged.

### Conclusion:
- The total energy of the hydrogen atom will change, the binding energy will remain unchanged, the kinetic energy will change, and the energy of the photon generated during de-excitation will remain unchanged.

### Final Answer:
- The correct options are: 1 (Total energy changes), 2 (Binding energy remains unchanged), and 4 (Photon energy remains unchanged).