Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?

Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?
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Answer :

1. Once the oxidation has reached the ketone stage, (primary alcohols on oxidation yield aldehyde where as secondary alcohols on oxidation yield a ketone), it is impossible to put more oxygen atoms on the relevant carbon atom without rupturing the backbone of the molecule.
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