A certain radionuclide is used to diagnose lymphoma. An atom of this radionuclide contains 31 protons and 36 neutrons. Which statement is correct about the radionuclide?

A. The atomic number is 31, the mass number is 67, and its symbol is [tex]_{31}^{67} \text{Ga}[/tex].

B. The atomic number is 31, the mass number is 67, and its symbol is [tex]_{57}^{31} \text{Ga}[/tex].

C. The atomic number is 67, the mass number is 31, and its symbol is [tex]_{31}^{67} \text{Ga}[/tex].

D. The atomic number is 67, the mass number is 31, and its symbol is [tex]_{67}^{31} \text{Ga}[/tex].



Answer :

Let's analyze the given information to determine the correct statement about the radionuclide. Here are the details provided:

- The atom of the radionuclide contains 31 protons.
- The atom of the radionuclide contains 36 neutrons.

### Step-by-Step Solution:

1. Determine the Atomic Number:
- The atomic number of an atom is defined as the number of protons it contains.
- Given that the atom contains 31 protons, the atomic number is therefore 31.

2. Determine the Mass Number:
- The mass number of an atom is defined as the total number of protons and neutrons.
- The given atom contains 31 protons and 36 neutrons.
- Therefore, the mass number can be calculated as:
[tex]\[ \text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons} \][/tex]
[tex]\[ \text{Mass Number} = 31 + 36 = 67 \][/tex]

3. Correct Symbol Notation:
- In the notation [tex]\(\ce{{}_Z^A \text{Element}}\)[/tex], [tex]\(Z\)[/tex] represents the atomic number, and [tex]\(A\)[/tex] represents the mass number.
- For our atom, the atomic number ([tex]\(Z\)[/tex]) is 31 and the mass number ([tex]\(A\)[/tex]) is 67.
- The chemical symbol for the element with atomic number 31 is Gallium (Ga).
- Therefore, the correct symbol notation for this radionuclide is:
[tex]\[ {}_{31}^{67} \text{Ga} \][/tex]

4. Evaluate the Given Statements:
- Statement 1: "The atomic number is 31, the mass number is 67, and its symbol is [tex]${}_{31}^{67} Ga$[/tex]."
- This statement is correct based on our calculations.
- Statement 2: "The atomic number is 31, the mass number is 67, and its symbol is [tex]${}_{57}^{31} Ga$[/tex]."
- This statement is incorrect because the symbol notation does not match the atomic and mass numbers.
- Statement 3: "The atomic number is 67, the mass number is 31, and its symbol is [tex]${}_{31}^{67} Ga$[/tex]."
- This statement is incorrect because the atomic and mass numbers are swapped.
- Statement 4: "The atomic number is 67, the mass number is 31, and its symbol is [tex]${}_{67}^{31} Ga$[/tex]."
- This statement is incorrect because both the atomic and mass numbers are incorrect.

Based on our evaluation, the correct statement is:

"The atomic number is 31, the mass number is 67, and its symbol is ${}_{31}^{67} \text{Ga}."