# Which of the following statements is correct?

## a. The greatest probability of finding a $\text{1s}$ electron is at the nucleus. b. The size of an orbital is directly proportional to its principal quantum number, c. A $\text{3p}$ orbital can hold three electrons. d. A $\text{2s}$ orbital is different from a $\text{1s}$ orbital because the $\text{2s}$ orbital requires more energy for the electrons to fill it.

Jan 28, 2017

d. $\text{2s}$ is different from $\text{1s}$ because the $\text{2s}$ requires more energy for the electrons to fill it.

#### Explanation:

a. This option is wrong.

The probability of finding electrons of any orbital in the nucleus is zero.

Here are the probability plots for $\text{1s, 2s}$, and $\text{3s}$ orbitals. (From Quora)

Notice that the probability is zero at the nucleus (0 pm).

b. This option is wrong.

The sizes of the orbitals are roughly proportional to ${n}^{2}$, where $n$ is the principal quantum number. Thus, the $\text{2s}$ orbital is about four times as big as a $\text{1s}$ orbital.

c. This option is wrong.

The Pauli Exclusion Principle states that no orbital can hold more than two electrons.

d. This option is correct.

$\text{2s}$ is different from $\text{1s}$ because the $\text{2s}$ requires more energy for the electrons to fill it.

A $\text{2s}$ orbital is bigger than a $\text{1s}$ orbital, and it takes energy to move an electron further away from the attraction of the nucleus.

Thus, a $\text{2s}$ orbital is higher in energy than a $\text{1s}$ orbital.