### Correct Option: C. 18 ### Detailed Explanation: To determine the maximum number of electrons that can occupy the N shell of an atom, we need to understand the structure of electron shells and the formula used to calculate the maximum number of electrons in a shell. 1. **Understanding Electron Shells**: - Electrons are arranged in shells around the nucleus of an atom. Each shell is designated by a principal quantum number (n), where n = 1, 2, 3, etc. - The N shell corresponds to n = 4. 2. **Formula for Maximum Electrons**: - The maximum number of electrons (E) that can occupy a shell is given by the formula: \[ E = 2n^2 \] - Here, \( n \) is the principal quantum number of the shell. 3. **Calculating for the N Shell**: - For the N shell, where \( n = 4 \): \[ E = 2(4^2) = 2(16) = 32 \] - Therefore, the maximum number of electrons that can occupy the N shell is **32**. ### Why the Other Options are Incorrect: - **Option A: 2** - This option is incorrect because the maximum number of electrons in any shell is not limited to just 2. The first shell (K shell, n=1) can hold a maximum of 2 electrons, but this does not apply to the N shell. - **Option B: 8** - This option is also incorrect. The second shell (L shell, n=2) can hold a maximum of 8 electrons, but again, this does not apply to the N shell. The N shell can hold many more electrons. - **Option D: 32** - This option is actually correct based on the calculation provided. The maximum number of electrons in the N shell is indeed 32, as calculated using the formula \( 2n^2 \). ### Common Pitfalls: - **Misunderstanding Shell Capacity**: Students often confuse the maximum number of electrons for different shells. Remember that each shell can hold a different maximum number of electrons based on its principal quantum number. - **Forgetting the Formula**: It’s crucial to remember the formula \( E = 2n^2 \) for calculating the maximum number of electrons in any shell. - **Confusing Shells with Subshells**: Each shell can contain subshells (s, p, d, f), but the maximum number of electrons is determined by the shell itself, not the subshells. ### Revision Summary: - The maximum number of electrons in a shell is calculated using the formula \( E = 2n^2 \). - For the N shell (n=4), the maximum number of electrons is 32. - Each shell has a different maximum capacity: K (2), L (8), M (18), N (32). - Always remember to apply the correct principal quantum number when calculating electron capacity.