Answer:
18 neutrons
Step-by-step explanation:
In the element;
₁₇Cl
The number of electrons in the chlorine atom is 17.
The mass number of chlorine is 35.
Mass number is the number of protons plus number of neutrons.
Mass number = Protons + neutrons
Neutrons = mass number - protons
Number of protons in chlorine is 17;
So;
Neutrons = 35 - 17 = 18