Which of the following is the correct isotope symbol for an atom containing 20 protons and 22 neutrons?

• A. ^{20}_{42}Ca
• B. ^{42}_{20}Ca
• C. ^{42}_{22}Ti
• D. ^{22}_{20}Ne

Answer: (B)

Verified step by step guidance

1. Identify the number of protons in the atom, which is given as 20. The number of protons defines the atomic number (Z), so here Z = 20.
2. Calculate the mass number (A) by adding the number of protons and neutrons: \(A = \text{protons} + \text{neutrons} = 20 + 22\).
3. Recall that the isotope symbol is written as \(^{A}_{Z}X\), where \(A\) is the mass number, \(Z\) is the atomic number, and \(X\) is the chemical symbol of the element.
4. Determine the chemical symbol for the element with atomic number 20, which is calcium (Ca).
5. Write the correct isotope symbol using the values found: the mass number as the superscript, the atomic number as the subscript, and the element symbol, resulting in \(^{42}_{20}Ca\).