Choose the following regarding Bohr model

Options

A. It introduce the concept of quantisation of energy
B. Radius of shellis given by ` r= ( 0.529n^(2))/( z) Å`
C. K.E. of electron is given by `( 2pi^(2) Me^(4) z^(2)k^(2))/( n^(2)h^(2))`
D. Two isotopes have same ionisation energy

Answer

To solve the question regarding the Bohr model, we will analyze each statement provided and determine whether it is true or false based on the principles of the Bohr model of the atom.

### Step-by-Step Solution:

1. **Statement 1: "It introduced the concept of quantization of energy."**
- The Bohr model indeed introduced the concept that electrons exist in discrete energy levels or "orbits" around the nucleus. This means that energy is quantized, and electrons can only occupy certain allowed energy levels.
- **Conclusion:** This statement is **True**.

2. **Statement 2: "The radius of cell given by R is equal to 0.529 n²/z angstrom."**
- According to the Bohr model, the radius of the nth orbit of an electron in a hydrogen atom is given by the formula \( R_n = 0.529 \frac{n^2}{Z} \) angstroms, where \( n \) is the principal quantum number and \( Z \) is the atomic number.
- **Conclusion:** This statement is **True**.

3. **Statement 3: "Kinetic energy of electron is given by 2π²m_e²Z²k²/n²h²."**
- The kinetic energy of an electron in a Bohr model can be expressed as \( KE = \frac{1}{2} m_e v^2 \) or in terms of energy levels as \( KE = \frac{13.6 Z^2}{n^2} \) eV. The given formula does not match the standard expressions for kinetic energy in the Bohr model.
- **Conclusion:** This statement is **False**.

4. **Statement 4: "Two isotopes have the same ionization energy."**
- Isotopes of an element have the same number of protons (and electrons) but differ in the number of neutrons. Since ionization energy depends primarily on the number of protons (nuclear charge) and the electron configuration, isotopes will have the same ionization energy.
- **Conclusion:** This statement is **True**.

### Final Conclusion:
Based on the analysis:
- Statements 1, 2, and 4 are **True**.
- Statement 3 is **False**.

Thus, the correct options are **a, b, and d**.