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Question
An element 'X' has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of 'X'. Also write group number, period number and valency of 'X'.
Solution
Mass number of X = 35
Number of neutrons = 18
Atomic number = Mass number – Number of neutrons
= 35 – 18 = 17
Electronic configuration of X = 2, 8, 7
Group of X = 17
Period of X = 3
Valency of X = 1
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