Question

An element has mass number 35and the no of neutrons is 18 identify the group no and period of
x​

Answer 1

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Answer 2

Mass number = 35

No. of neutron = 18

But,

mass no. = no. of (proton+neutron)

=> 35 = 18 + no. of proton

=> no. of proton = 35 - 18

=> no. of proton = 17

But, no. of proton = no. of electron

.°. no. of electron = 17

now, see the electronic configuration,

K = 2

L = 8

M = 7

It means, in the last shell, there are 7 electrons,

therefore,

Group number = $\bold{17}$

and , there are 3 shells occupying electrons,

Therefore,

Period number = $\bold{3}$

Hence,

the element is $\bold{CHLORINE}$