First of all, there are two compounds, one is H2O and the other is H2O2.

First of all, there are six combinations of H2O and H2, 1 1, 22,33, 12,13,23, and two kinds of oxygen, namely 16 and 18. Their combination results are as follows.

Look at H2O2 again. Similarly, there are six kinds of H2 and three kinds of O2, namely 16 and 16, 16 and 18, 18 and 18, so the combination is 6 * 3 =/kloc-0. This has also been said. However, when H2 chooses 12, 13 and 23, the two H's are asymmetric, so there is one more O2 case: 18 and 18 H2. H1o16 o18h3 is different, and H2 O 18 O 16 H3 is different.

One ***33 species

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