Question 4: Choose the correct answer to the following question: Know that well water often contains many impurities. To remove impurities, people put well water into the filter tank, the bottom of the tank is lined with layers of fine sand, gravel and charcoal. The water flowing through these layers will be clearer. Which of the following statements is not correct?
ANSWER
The effect of the lining:
The layer of charcoal has the effect of absorbing organic substances and bacteria.
The fine sand layer has the effect of keeping the soil and sand particles in place.
– The gravel layer has the effect of filtering and retaining small-sized suspended components.
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