Question

X is a gaseous element. Its atomic number is 17. Its mass number is 35.
Find out the number of electrons, protons and neutrons.

TNSCERT Class 9 General Science Ch4 Atomic Structure

Answer 1

protons=electrons=atomic number=17
neutrons=mass no - atomic no=35-17=18

Answer 2

chlorine has atomic no. 17 n mass no. 35
no. of protons = at. no. 
no. of protons is 17
no. of protons= no. of electrons
no. of electrons = 17
mass no. = no. of protons + no. of neutrons
35= 17+ no. of neutrons
no. of neutrons = 35- 17
no. of neutrons= 18