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Science · 2023 · 2 marks
CBSE 2023 · Region 2 · Set 1 · Q26
We do not clean ponds or lakes but an aquarium needs to be cleaned regularly. Why ?
Marking-scheme solution
An aquarium is a man-made ecosystem in which natural cleansing agents like decomposers are not present, so needs periodic cleaning;
ponds and lakes are natural ecosystems which have natural cleansing agents. (Decomposers)
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CBSE Class 10 Science past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.