How many maximum electrons can M shell have?

18

The correct answer is option 1. 18.

In atomic physics, electrons are arranged in energy levels or shells around the nucleus of an atom. The M shell, also known as the third shell or the n=3 shell, is one of these energy levels. The maximum number of electrons that can be accommodated in a given shell can be determined using the formula \(2n^2\), where \(n\) is the principal quantum number of the shell.

For the M shell (\(n=3\)):
\[ 2 \times (3)^2 = 2 \times 9 = 18 \]

Therefore, the M shell can have a maximum of 18 electrons. The electrons in an atom fill the available shells in a specific order according to the Aufbau principle, Pauli exclusion principle, and Hund's rule. The filling order for the first few shells is:

1. K shell (n=1): Maximum of 2 electrons

2. L shell (n=2): Maximum of 8 electrons

3. M shell (n=3): Maximum of 18 electrons

The maximum number of electrons in a shell increases with the principal quantum number (\(n\)). As you move to higher energy levels, more subshells become available, allowing for the accommodation of additional electrons.