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Which law makes it necessary for a chemical equation to be balanced?
AThe law of definite proportions
BThe law of multiple proportions
CThe law of constant composition
DThe law of conservation of matter
Answer & Solution
Correct answer: D. The law of conservation of matter
1. A balanced equation shows equal numbers of atoms of each element on both sides.
2. Atoms are neither created nor destroyed during a chemical change.
3. That is the law of conservation of matter, so balance is required to stay consistent with it.
4. Confirm balance by multiplying each coefficient by the matching subscript and comparing totals.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 4 "Stoichiometry of Chemical Reactions", section 4.1 Writing and Balancing Chemical Equations_
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