The first electron shell which is the nearest to the nucleus never holds more than 'n' electrons, where 'n' is equal to:

2

The correct answer is option 3. 2.

In an atom, electrons are arranged in energy levels called electron shells. The first electron shell, often denoted as the K shell, is the closest to the nucleus. According to the Aufbau principle, electrons fill the lowest energy levels first before occupying higher energy levels.

The first electron shell, or K shell, consists of only one subshell, which is the 1s orbital. The 1s orbital can hold a maximum of 2 electrons. This limitation is based on the Pauli exclusion principle, which states that no two electrons in an atom can have the same set of quantum numbers. Specifically, in the 1s orbital, electrons have different spin states, either spin up or spin down, which allows for a maximum of 2 electrons to occupy this orbital.

Therefore, the first electron shell can never hold more than 2 electrons. This is why the correct answer is  2.