Which isotope of fluorine has 10 neutrons?

• A. F-17
• B. F-20
• C. F-19
• D. F-18

Answer: (C)

Verified step by step guidance

1. Recall that the number of neutrons in an isotope is given by the difference between the mass number (A) and the atomic number (Z): \(\text{Number of neutrons} = A - Z\).
2. Identify the atomic number of fluorine (F), which is the number of protons. For fluorine, \(Z = 9\).
3. For each isotope, the mass number \(A\) is the number after the element symbol (e.g., for F-17, \(A = 17\)).
4. Calculate the number of neutrons for each isotope by subtracting the atomic number from the mass number: \(\text{neutrons} = A - 9\).
5. Find the isotope where the number of neutrons equals 10 by solving \(A - 9 = 10\), which gives \(A = 19\). Therefore, the isotope with 10 neutrons is F-19.