Answer : The correct option is, (B) 17
Explanation :
Atomic number is defined as the number of protons or number of electrons.
Atomic number = number of protons = number of electrons
Mass number is defined as the sum of number of protons and number of neutrons.
Number of neutrons = Mass number - Number of protons
As we are given that:
Number of protons in chlorine atom = 17
Number of neutrons in chlorine atom = 18
For neutral atom :
As, Atomic number = number of protons = number of electrons
So, Number of electrons in chlorine atom = Number of protons = 17
Hence, the correct option is (B) 17