How many atoms are there in 3 water molecules?
a. 3
b. 2
c. 9
d. 6
The correct answer and explanation is:
Correct Answer: c. 9
Each water molecule is made up of three atoms. These include two hydrogen (H) atoms and one oxygen (O) atom. This gives a total of three atoms per water molecule. The molecular formula for water is H₂O, which represents its atomic composition.
To find how many atoms are in 3 water molecules, you multiply the number of atoms in one molecule by three:
- One H₂O molecule contains 2 hydrogen atoms and 1 oxygen atom
- Total atoms in one water molecule = 2 (H) + 1 (O) = 3 atoms
- Atoms in three water molecules = 3 × 3 = 9 atoms
This kind of calculation relies on understanding how chemical formulas indicate the types and numbers of atoms in a compound. The subscript in a chemical formula tells how many atoms of each element are present in a single molecule. In H₂O, the subscript 2 indicates there are two hydrogen atoms, and no subscript next to oxygen means there is one oxygen atom.
Counting atoms becomes especially important in chemical reactions, where the law of conservation of mass applies. This law says that matter cannot be created or destroyed in a chemical reaction. All atoms present in the reactants must also be accounted for in the products. For accurate calculations in chemistry, such as determining mass or predicting reaction outcomes, knowing the number of atoms involved is essential.
Therefore, if you have three water molecules, you have a total of 9 atoms: six hydrogen atoms and three oxygen atoms. This makes option c. 9 the correct answer.