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ASVAB · Chemistry

What does the chemical formula H₂O represent, and what do the symbols mean?

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Correct answer

Water — two hydrogen atoms bonded to one oxygen atom

  1. A Oxygen gas
  2. B Two hydrogen atoms only
  3. C Water — two hydrogen atoms bonded to one oxygen atom
  4. D Hydrogen peroxide

Why this is the answer

H₂O is the chemical formula for water. The subscript 2 after H means there are two hydrogen atoms, and the O (with an implied subscript of 1) means one oxygen atom, so each water molecule is two hydrogen atoms bonded to one oxygen atom. Hydrogen peroxide is a different compound, H₂O₂ (two hydrogens and two oxygens). Reading chemical formulas — where subscripts give the number of each atom — is a basic chemistry skill. Water's formula H₂O is one of the most important to recognize.
Source: ASVAB GS, Chemical Formulas

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About this topic: Chemistry

Chemistry questions cover atomic structure, the periodic table, chemical versus physical changes, acids and bases, and basic reactions. Expect symbols, states of matter and the difference between an element, a compound and a mixture. This is one of 12 General Science questions on chemistry, each with a full explanation on a single study page.

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