Standard Science Primary 3 Diversity

Why do fish die if the water in their tank is boiled and then cooled down before they are put back in, unless the water is stirred or aerated first?

A Boiling removes the dissolved air from the water.
B The fish cannot see in boiled water.
C The water becomes poisonous.
D The water is too salty.
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Worked Solution

Step 1: Living things need air to survive. Step 2: Fish breathe dissolved oxygen in water. Step 3: Boiling drives out dissolved gases; without aeration, the fish will suffocate.

Correct answer: Boiling removes the dissolved air from the water.

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