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Question

Chemistry Question on Structure of atom

The electronic configuration of a dipositive ion M2+{{M}^{2+}} is 2,8,142, 8, 14 and its mass number is 5656. The number of neutrons present is

A

32

B

42

C

30

D

34

Answer

30

Explanation

Solution

Number of electrons in M2+=24{{M}^{2+}}=24 \therefore number of electrons in M=26M=26 i.e., atomic number (Z)=26(Z)=26 Mass number (A)=56(A)=56 \therefore number of neutrons =AZ=5626=30=A-Z=56-26=30 .