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The diagram shows changes in the concentrations of two substances X and Y in the sewage river polluted. What are the substances X and Y? `{:(" X",," Y"),("(a) Carbon dioxide",-,"Oxygen"),("(b) Oxygen",-,"Nitrogen compound"),("(c) Carbon dioxide",-,"Nitoregn compound"),("(d) Nitrogen compound",-,"Carbon dioxide"):}` |
Answer» Correct Answer - B | |