As electron moves away from the nucleus, its

Options

A. K.E. decreases and P.E. increases
B. Both K.E. and P.E. decrease
C. Both K.E. and P.E. increase
D. K.E. increases but P.E. decreases.

Explanation

To solve the question "As an electron moves away from the nucleus, its...", we will analyze the behavior of kinetic energy and potential energy of the electron according to Bohr's model of the atom.

### Step-by-Step Solution:

1. **Understanding the Concept**: According to Bohr's model, the energy of an electron in an atom can be described in terms of its kinetic energy (KE) and potential energy (PE). As the electron moves away from the nucleus, we need to analyze how these energies change.

2. **Kinetic Energy (KE)**: The formula for the kinetic energy of an electron is given by:
\[ KE = \frac{Z e^2}{2r} \]
where \( Z \) is the atomic number, \( e \) is the charge of the electron, and \( r \) is the radial distance from the nucleus.

3. **Effect of Increasing Distance (r)**: As the electron moves away from the nucleus, the radial distance \( r \) increases. Since \( r \) is in the denominator of the kinetic energy formula, an increase in \( r \) leads to a decrease in kinetic energy:
\[ \text{As } r \text{ increases, } KE \text{ decreases.} \]

4. **Potential Energy (PE)**: The potential energy of the electron is given by:
\[ PE = -\frac{Z e^2}{r} \]
Again, as \( r \) increases, the absolute value of the potential energy decreases (becomes less negative), which means that the potential energy increases:
\[ \text{As } r \text{ increases, } PE \text{ increases.} \]

5. **Conclusion**: Therefore, as the electron moves away from the nucleus:
- Kinetic Energy decreases.
- Potential Energy increases.

6. **Final Answer**: The correct option is that the kinetic energy decreases and the potential energy increases.