Read the following text and answer the following questions on the basis of the same:
Band theory of solid:
Consider that the Si or Ge crystal contains N atoms. Electrons of each atom will have discrete energies in different orbits. The electron energy will be same if all the atoms are isolated, i.e., separated from each other by a large distance. However, in a crystal, the atoms are close to each other (2 Å to 3 Å) and therefore the electrons interact with each other and also with the neighbouring atomic cores. The overlap (or interaction) will be more felt by the electrons in the outermost orbit while the inner orbit or core electron energies may remain unaffected. Therefore, for understanding electron energies in Si or Ge crystal, we need to consider the changes in the energies of the electrons in the outermost orbit only. For Si, the outermost orbit is the third orbit (n = 3), while for Ge it is the fourth orbit (n = 4). The number of electrons in the outermost orbit is 4 (2s and 2p electrons). Hence, the total number of outer electrons in the crystal is 4N. The maximum possible number of outer electrons in the orbit is 8 (2s + 6p electrons). So, out of the 4N electrons, 2N electrons are in the 2N s-states (orbital quantum number l = 0) and 2N electrons are in the available 6N p-states. Obviously, some p-electron states are empty. This is the case of well separated or isolated atoms.
For Silicon and Germanium the outermost orbits are respectively:

Options

A. n = 3 and n = 5
B. n = 4 and n = 3
C. n = 5 and n = 4
D. n = 3 and n = 4

Explanation

To solve the question regarding the outermost orbits of Silicon (Si) and Germanium (Ge) based on the provided text, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Key Information**:
- The question specifically asks about the outermost orbits of Silicon and Germanium.
- The relevant information is found towards the end of the provided text.

2. **Read the Relevant Section**:
- The text states: "For Si, the outermost orbit is the third orbit (n = 3), while for Ge it is the fourth orbit (n = 4)."

3. **Summarize the Findings**:
- For Silicon (Si), the outermost orbit is n = 3.
- For Germanium (Ge), the outermost orbit is n = 4.

4. **Formulate the Answer**:
- The outermost orbits for Silicon and Germanium are respectively: n = 3 for Si and n = 4 for Ge.

5. **Check the Options**:
- Compare the findings with the provided options to select the correct one.

### Final Answer:
- The outermost orbits for Silicon and Germanium are respectively: n = 3 (for Si) and n = 4 (for Ge).

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