Question

one isotope of sodium has 11 protons and 7 neutrons. what is the mass number of this isotope?
4
7
11
18

Explanation:

Step1: Recall the formula for mass number

Mass number \(A=\) number of protons \(Z+\) number of neutrons \(N\)

Step2: Substitute the given values

Given \(Z = 11\) (protons) and \(N=7\) (neutrons). Then \(A=11 + 7\)

Step3: Calculate the mass number

\(A=18\)

Answer:

18