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Question
Which pair of atomic numbers represents elements in the same group?
Options
11, 19
6, 12
4, 16
8, 17
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Solution
11, 19
Explanation:
Elements in the same group share the same number of valence electrons and exhibit similar chemical properties. To find the group, we look at the electronic configuration:
- Atomic number 11 (Sodium, Na): Configuration is 2, 8, 1. It has 1 valence electron (Group 1).
- Atomic number 19 (Potassium, K): The configuration is 2, 8, 8, 1. It also has 1 valence electron (Group 1).
Since both have 1 valence electron, they belong to the same group (Group 1, the Alkali Metals).
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