Write the electronic configuration of any one pair of isotopes and isobar.
ScienceClass 9CBSEAnswered 27 Mar 2026
Answer
(a) Isotopes: Isotopes are atoms which have the same number of protons, but the number of neutrons differs. This leads to the variation in mass number too.
Example: Carbon molecule exists as 6C12 and 6C14, but when their electronic configuration is noticed, both have K-2; L-4
(b) Isobars: Isobars are atoms which have the same mass number but differ in atomic number. The electronic configuration of an isobar pair is as follows:
Example: Electronic configuration of 20Ca40 – K-2; L-8; M-8; N- 2
Electronic configuration of 18Ar40 – K-2; L-8; M-8
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