Which of the following is the correct nuclear symbol for the isotope of argon with mass number 38?

• A. ^{38}_{18}Ar
• B. ^{38}_{17}Ar
• C. ^{38}_{20}Ar
• D. ^{18}_{38}Ar

Answer: (A)

Verified step by step guidance

1. Recall that the nuclear symbol for an isotope is written as \(^{A}_{Z}X\), where \(A\) is the mass number (total number of protons and neutrons), \(Z\) is the atomic number (number of protons), and \(X\) is the chemical symbol of the element.
2. Identify the atomic number (\(Z\)) of argon from the periodic table. Argon has an atomic number of 18, meaning it has 18 protons.
3. Use the given mass number (\(A\)) of 38 for the isotope. This number represents the sum of protons and neutrons in the nucleus.
4. Construct the nuclear symbol by placing the mass number 38 as a superscript and the atomic number 18 as a subscript to the left of the chemical symbol 'Ar'. This gives \(^{38}_{18}Ar\).
5. Verify that the other options are incorrect because they either have the wrong atomic number for argon or incorrectly place the numbers (e.g., swapping mass and atomic numbers).