Question

what are the number of neutron in37 Cl 17

Answer 1

Neutron in an atom is given by
Mass no. -- Atomic no.

So in Cl 17 no. Of neurons will be 37-17 which is equal to 20.

Hope you get your answer.

Answer 2

neutron = mass - atomic number
             = 37- 17
             = 20
therefore,,the no. of neutrons are 20