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22/11/2020 4:09 pm
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The atomic number of three elements are given below:
Element (symbol) - A - B - C
Atomic number - 5 - 7 - 10
Write the symbol of the element which belongs to (o) group 13, (b) group 15, of the periodic table. State the period of the periodic table to which these elements belong. Give reason for your answer.
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22/11/2020 4:10 pm
(a) A belongs to group 13 because its electronic configuration is 2, 3, ie. it has 3 valence electrons.
(b) ‘B’ belongs to group 15 because its electronic configuration is 2, 5, ie. it has 5 valence electrons.
They belong to 2nd period as they both have two shells.