Bohr’s theory based on the Planck’s quantum theory.

Answer

**Step-by-Step Solution:**

1. **Understanding Planck's Quantum Theory:**
- Planck's quantum theory states that energy is not emitted or absorbed continuously, but rather in discrete packets called quanta. This means that atoms and molecules can only emit or absorb energy in specific quantities.

2. **Energy and Frequency Relationship:**
- According to Planck's theory, the energy (E) of these quanta is directly proportional to their frequency (ν). This relationship is expressed mathematically as:
\[ E = hν \]
where \( h \) is Planck's constant.

3. **Overview of Bohr's Theory:**
- Bohr's theory, proposed in 1913, describes the behavior of electrons in atoms. It suggests that electrons occupy specific energy levels or orbits around the nucleus. When an electron transitions between these orbits, it either absorbs or emits energy.

4. **Electron Transitions:**
- When an electron moves to a higher energy level (excitation), it absorbs energy, typically in the form of radiation. Conversely, when it falls to a lower energy level (de-excitation), it emits energy as radiation.

5. **Connection Between Bohr's Theory and Planck's Quantum Theory:**
- Bohr's theory is fundamentally based on the principles of Planck's quantum theory. The quantization of energy levels in Bohr's model directly stems from the idea that energy changes occur in discrete amounts, as described by Planck.

6. **Conclusion:**
- Therefore, the statement that "Bohr’s theory is based on Planck’s quantum theory" is true. Bohr's model incorporates the concept of quantized energy levels, which aligns with the principles established by Planck.

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