To solve the question, we need to analyze the assertion (A) and the reason (R) given in the statement regarding the Bohr model of the atom.
### Step 1: Understanding the Assertion (A)
The assertion states that in the Bohr model, the frequency of revolution of an electron in its orbit is not connected to the frequency of the spectral line for smaller principal quantum numbers (n).
- In the Bohr model, the frequency of revolution (f) of an electron in its nth orbit is given by:
\[
f = \frac{Z^2 \cdot m \cdot e^4}{4 \pi \epsilon_0^2 \cdot h^3 \cdot n^3}
\]
where Z is the atomic number, m is the mass of the electron, e is the charge of the electron, \(\epsilon_0\) is the permittivity of free space, and h is Planck's constant.
- For smaller values of n (i.e., n = 1, 2), the frequency of revolution does not depend on n in a way that it affects the spectral lines significantly. The spectral lines are determined by transitions between energy levels, which are quantized.
### Step 2: Understanding the Reason (R)
The reason states that for transitions between large quantum numbers, the frequency of revolution of an electron in its orbit is connected to the frequency of a spectral line, as per Bohr's Correspondence Principle.
- The Correspondence Principle states that the behavior of quantum systems should converge to classical physics as the quantum numbers become very large (n → ∞).
- For large n, the energy levels become closer together, and the frequency of revolution becomes more relevant to the spectral lines observed. In this case, the frequency of the electron's revolution can be approximated to be proportional to the frequency of the emitted or absorbed spectral lines.
### Step 3: Conclusion
- The assertion (A) is **correct** because for smaller principal quantum numbers, the frequency of revolution does not correlate with the frequency of spectral lines.
- The reason (R) is also **correct** because for large principal quantum numbers, the frequency of revolution does correlate with the frequency of spectral lines due to the Correspondence Principle.
Thus, both the assertion and reason are correct, and the reason correctly explains the assertion.
### Final Answer
Both the assertion (A) and reason (R) are correct, and R is the correct explanation of A.
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