To determine how many neutrons are present in a single [tex]\(Fe^{2+}\)[/tex] atom with a mass number of 56, we can follow these steps:
1. Identify the atomic number of iron (Fe): The atomic number of iron (Fe) is 26. The atomic number corresponds to the number of protons in the nucleus.
2. Understand the mass number: The mass number represents the total number of protons and neutrons in the nucleus of an atom. For this problem, the mass number is given as 56.
3. Use the relationship between mass number, protons, and neutrons:
The formula to find the number of neutrons is:
[tex]\[
\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}
\][/tex]
Substituting the values, we have:
[tex]\[
\text{Number of neutrons} = 56 - 26
\][/tex]
4. Perform the subtraction:
[tex]\[
56 - 26 = 30
\][/tex]
Therefore, a single [tex]\(Fe^{2+}\)[/tex] atom with a mass number of 56 has [tex]\(30\)[/tex] neutrons.
The correct answer is:
[tex]\[
30
\][/tex]
