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NDA 2024 GAT · General Knowledge · Atomic Structure, Periodic Table and Bonding · hard

Among the elements Na, Mg, Al and Si of the third period, the one with the largest atomic radius is

Single correct option

Among the elements Na, Mg, Al and Si of the third period, the one with the largest atomic radius is
  1. A. Mg
  2. B. Al
  3. C. Si
  4. D. Na
Show answer and solution

Answer: (D) Na

Within a period the nuclear charge increases while the electrons are added to the same shell, so atoms shrink from left to right. Na is the first of these in the period and therefore has the largest radius. Si, at the right end, is the smallest. The trap is to expect size to rise with atomic number.
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Original question written in the NDA 2024 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake