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Q113
(NDA-II/2024)
Science & Technology › Basic Science (Physics, Chemistry, Biology)
Official Key
What is the maximum number of electrons that can occupy the first shell of an atom ?
Explanation
The distribution of electrons in different orbits or shells of an atom is governed by the Bohr-Bury scheme. According to this rule, the maximum number of electrons that can be accommodated in a shell is given by the formula 2n2, where 'n' is the orbit number or energy level index.
- For the first shell (K shell), n = 1.
- Applying the formula: 2 × (1)2 = 2 × 1 = 2.
Therefore, the maximum number of electrons that can occupy the first shell is 2. For comparison, the second shell (L shell, n=2) can hold a maximum of 8 electrons (2 × 22), and the third shell (M shell, n=3) can hold up to 18 electrons (2 × 32).
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