Select the correct answer.

For [tex]\(Al\)[/tex], its atomic number is 13 and its mass number is 27. How many neutrons does it have?

A. 13

B. 14

C. 26

D. 27

E. 40



Answer :

To determine the number of neutrons in an Aluminum ([tex]\(Al\)[/tex]) atom, we start by understanding two important concepts:

1. Atomic Number: The atomic number of an element is the number of protons in the nucleus of an atom of that element. For Aluminum, the atomic number is 13. This means that an Aluminum atom has 13 protons.

2. Mass Number: The mass number of an element is the total number of protons and neutrons in the nucleus. For Aluminum, the mass number is 27.

To find the number of neutrons, we use the relationship:
[tex]\[ \text{Number of neutrons} = \text{Mass number} - \text{Atomic number} \][/tex]

For Aluminum:
[tex]\[ \text{Number of neutrons} = 27 - 13 \][/tex]

Calculating this difference:
[tex]\[ \text{Number of neutrons} = 14 \][/tex]

Therefore, the number of neutrons in an Aluminum atom is [tex]\(14\)[/tex].

So, the correct answer is:
B. 14

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