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Which balanced equation represents a chemical change?
A) H2O() + energy → H2O(g)
B) 2H2O() + energy → 2H2(g) + O2(g)
C) H2O() → H2O(s) + energy
D) H2O(g) → H2O() + energy
What is the reason behind the answer? (B)
1 Answer
- hcbiochemLv 71 year ago
In the other three answers, you are simply changing the state of water. You begin with H2O and end with H2O. These are all physical changes. In B, you decompose water into hydrogen gas and oxygen gas. That is a chemical process and not a physical one because you are changing the identity of the substance.
