CBSC Session 2022-23.
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Four elements P,Q,R and S belong to the third period of the Modern Periodic Table and have respectively 1, 3, 5 and 7 electrons in their outermost shells. Write the electronic configurations of Q and R and determine their valencies. Write the molecular formula of the compound formed when P and S combine.
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Elements P,Q R and S are the elements of third period, these must have three filled shells.
Electronic configuration of R: 2,8,5
Valency of R: 8-5 = 3
Electronic configuration of P: 2,8,1
Electronic configuration of S: 2,8,7
:Formula of the compound formed by the combination of P and S: PS/NaCI.