Statement 1: In Bohr's model, velocity of electron increases with decrease in positive charge of nucleus as electrons are not held tightly.
Statement 2: Velocity decreases with an increase in principal quantum number

Options

A. Statement 1 is true, Statement 2 is true, Statement 2 is the correct explanation of statement 1.
B. Statement 1 is true, Statement 2 is false
C. Statement 1 is flase, Statement 2 is true
D. Statement 1 is false, Statement 2 is false

Answer

To solve the question, we need to analyze both statements based on Bohr's model of the atom.

### Step-by-Step Solution:

1. **Understanding Statement 1**:
- The statement claims that in Bohr's model, the velocity of an electron increases with a decrease in the positive charge of the nucleus.
- According to Bohr's model, the velocity \( V_n \) of an electron in a hydrogen-like atom is given by the formula:
\[ V_n = V_0 \cdot \frac{Z}{n} \]
where \( V_0 \) is a constant, \( Z \) is the atomic number (number of protons, which represents the positive charge of the nucleus), and \( n \) is the principal quantum number.
- From this equation, we can see that the velocity \( V_n \) is directly proportional to the atomic number \( Z \). Therefore, if the positive charge of the nucleus (i.e., \( Z \)) decreases, the velocity \( V_n \) will also decrease, not increase.
- **Conclusion**: Statement 1 is **incorrect**.

2. **Understanding Statement 2**:
- The statement claims that the velocity decreases with an increase in the principal quantum number \( n \).
- From the same formula \( V_n = V_0 \cdot \frac{Z}{n} \), we can see that as the principal quantum number \( n \) increases, the denominator increases, which leads to a decrease in the velocity \( V_n \).
- **Conclusion**: Statement 2 is **correct**.

3. **Final Evaluation**:
- Since Statement 1 is incorrect and Statement 2 is correct, we conclude that the overall evaluation of the statements is:
- Statement 1: False
- Statement 2: True

### Final Answer:
- Statement 1 is incorrect, and Statement 2 is correct.

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