The first use of quantam theroy to explain the structure of atom was made by :

Options

A. 1.Heisenberg
B. 2.Bohr
C. 3.Planck
D. 4.Einstein

Explanation

To solve the question regarding who first used quantum theory to explain the structure of the atom, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Quantum Theory**:
- Quantum theory is a fundamental theory in physics that describes the physical properties of nature at the scale of atoms and subatomic particles. It introduces concepts such as quantization of energy, wave-particle duality, and the uncertainty principle.

2. **Historical Context**:
- The development of quantum theory was a significant milestone in understanding atomic structure. Various scientists contributed to the development of quantum mechanics, but we need to identify who first applied it to atomic structure.

3. **Identifying Key Figures**:
- The question provides four options: Heisenberg, Bohr, Planck, and Einstein. We need to evaluate their contributions to atomic theory:
- **Max Planck**: Introduced the concept of quantization of energy but did not explain atomic structure.
- **Albert Einstein**: Contributed to the photoelectric effect and quantum theory but did not focus on atomic structure.
- **Werner Heisenberg**: Known for the uncertainty principle, which came later in the development of quantum mechanics.
- **Niels Bohr**: In 1913, he proposed the Bohr model of the atom, which incorporated quantum theory to explain the stability of electrons in atoms and the emission of spectral lines.

4. **Conclusion**:
- Based on the historical contributions, Niels Bohr was the first to use quantum theory to explain the structure of the atom. Therefore, the correct answer to the question is **Niels Bohr**.

### Final Answer:
The first use of quantum theory to explain the structure of the atom was made by **Niels Bohr**.

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