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Question: Three elements ‘X’, ‘Y’ and ‘Z’ have atomic numbers 18, 19 and 20 respectively. how many electrons a...

Three elements ‘X’, ‘Y’ and ‘Z’ have atomic numbers 18, 19 and 20 respectively. how many electrons are present in the M shells of these elements?

A

8, 9, 10

B

8, 10, 13

C

8, 8, 8

D

8, 9, 12

Answer

8, 8, 8

Explanation

Solution

: 18X=1s2,2s2,2p6,⎵3s2,3p618X = 1s^{2},2s^{2},2p^{6},\underset{}{\overset{3s^{2},3p^{6}}{⎵}}

19Y=1s2,2s2,2p6,⎵3s2,3p6,4s119Y = 1s^{2},2s^{2},2p^{6},\underset{}{\overset{3s^{2},3p^{6}}{⎵}},4s^{1}

20Z=1s2,2s2,2p6,⎵3s2,3p6,4s220Z = 1s^{2},2s^{2},2p^{6},\underset{}{\overset{3s^{2},3p^{6}}{⎵}},4s^{2}