Multiple choice

In which of the following processes oxygen is not used up?

  1. Combustion

  2. Respiration

  3. Formation of oxides

  4. Photosynthesis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Photosynthesis produces oxygen as a byproduct, it does not consume it. Combustion and respiration both use oxygen to produce energy, while oxide formation involves oxygen reacting with other elements.

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