Multiple choice

The smallest of all atoms are

  1. Helium atoms

  2. Hydrogen atoms

  3. Oxygen atoms

  4. Uranium atoms
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hydrogen atoms are the smallest because hydrogen has the lowest atomic number (1), meaning it has only one proton and typically one electron. Helium has 2 protons and electrons, oxygen has 8, and uranium has 92. The size of an atom is primarily determined by its number of protons and electron shells.

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