AN ELEMENT X HAS MASS NO.' 35 N NUMBER OF NEUTRONS 18.
1.ATOMIC NO. OF X?
we know that
atomic mass = no. of protons + no. of neutrons
no. of protons= atomic no.
in this case,
the atomic mass = 35 and
no. of neutrons = 18
so the no. of prontons(atomic number of x) = 35-18 = 17
hence, the atomic number of x is 17 and the element is chlorine
hope it helps......