Question

question 1 (1 point)
an atom with an atomic number of 31 and a mass number of 72 contains:
o a 72 protons, 31 electrons, 31 neutrons
o b 31 protons, 31 electrons, 41 neutrons
o c 31 protons, 31 electrons, 31 neutrons
o d 31 protons, 31 electrons, 30 neutrons

Explanation:

Step1: Determine the number of protons and electrons

The atomic number \(Z\) of an atom is equal to the number of protons and also equal to the number of electrons in a neutral atom. Given \(Z = 31\), so the number of protons \(p=31\) and the number of electrons \(e = 31\).

Step2: Calculate the number of neutrons

The mass number \(A\) of an atom is given by the formula \(A=p + n\), where \(n\) is the number of neutrons. We know \(A = 72\) and \(p=31\). Rearranging the formula for \(n\), we get \(n=A - p\). Substituting the values: \(n=72-31=41\).

Answer:

B. 31 protons, 31 electrons, 41 neutrons