MCQ
Which of the following substance cannot be broken down by a chemical method?
- AAmmonia $\left(\mathrm{NH}_3\right)$
- ✓Helium $(\mathrm{He})$
- CMethane $\left(\mathrm{CH}_4\right)$
- DWater $\left(\mathrm{H}_2 \mathrm{O}\right)$
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