An element is a pure substance that cannot be separated or divided into simpler substances by any method (physical or chemical). The four common elements in all the living organisms are carbon, oxygen, hydrogen, nitrogen.
Thus, the four elements that make up about 96 % of body matter are carbon, oxygen, hydrogen, nitrogen (c).
Reduction involves the either the addition of hydrogen and removal of oxygen.
<h3>What is reduction?</h3>
Reduction involves the removal of oxygen.
This implies there is a loss of oxygen in reduction.
This can be represented in the extraction of iron from it ores.
Fe₂O₃ + 3CO → 2Fe + 3CO₂
Reduction is also the addition of hydrogen. This implies it is the gain of hydrogen.
For example
CH₃CHO → CH₃CH₂OH
learn more on reduction here: brainly.com/question/9485345
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