How many neutrons are present in an atom of chlorine-35?

• A. 35
• B. 20
• C. 18
• D. 17

Answer: (C)

Verified step by step guidance

1. Identify the atomic number of chlorine, which is the number of protons in the atom. For chlorine, the atomic number is 17.
2. Recognize that the number 35 in chlorine-35 represents the mass number, which is the total number of protons and neutrons in the nucleus.
3. Use the formula to find the number of neutrons: \(\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}\).
4. Substitute the known values into the formula: \(\text{Number of neutrons} = 35 - 17\).
5. Calculate the difference to find the number of neutrons in chlorine-35.