Multiple choice general knowledge

Some communities banned detergents containing high levels of phosphates because...

  1. phosphates cause chemical reactions that raise the temperature of river and lake water, disrupting ecosystems.

  2. phosphates are not efficient cleansers.

  3. excessive phosphates in lakes may begin a process that causes fish to suffocate and die.

  4. phosphates kill algae and disrupt normal food webs in lakes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Phosphates act as fertilizers in water bodies, causing excessive algae growth (eutrophication). When algae die and decompose, bacteria consume oxygen during decomposition, depleting dissolved oxygen levels. This oxygen depletion causes fish to suffocate and die, not the phosphates directly killing algae.

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