Question

The atomic number of an element is 4 and mass number is 9 then :

(A) what is the number of proton and neutron in it?

(B) write electronic configuration of it.

(C) what will be the valency of this element.

Answer 1

a) no. of proton = atomic number

=4

no. of neutron = mass no.- proton

= 5

b) ELECTRONIC CONFIGURATION

2,2

c)valency =2

Answer 2

Atomic number=4

mass number =9

element name = beryllium

no. of protons =4

no . of neutrons =5

electronic configuration =1s²2s²=He2s²

valency=2

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