Question

I want the answer fast​

Answer 1

Since the electronic configuration is of ground state,

a) atomic number = 2+8+7 = 17

b) the atom needs one more electron to achieve octet or eight electrons in outermost shell. Hence valency is 1

c) Magnesium has a valency of 2, that is it can donate two electrons. The given atom is only capable of recieving one electron, so two such atoms will combine with one magnesium atom. So if we take the atom as 'X', its formula would be MgX₂

d) Mass number = no. of protons + no. of neutrons

                           = atomic number + no. of neutrons

Given,

mass number = 35

atomic number = 17

So, 35 = 17 + no. of neutrons

no. of neutrons = 18

HOPE THIS HELPS!!