The atomic number and the mass number of certain elements are given below in the table.
(i) Select a pair of isobar and isotope from the above table.
(ii) What would be the valency of elements B and E?
(i) Pair of isotope are A and F because they have the same atomic number.
Pair of isobar are D and E because they have the same mass number.
(ii) Valency of element B can be determined by electronic configuration, for the element B is 2, 1. The valency is 1.
Electronic configuration for E is 2, 8, 8, 2. So the valency is 2.
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