Chemistry question makes all 4 contestants of Road to Olympia give up

Let's try our best to challenge all 4 candidates on the way to Olympia.

The 30-point question in the Finish Line section of the Road to Olympia, although very realistic and close to life, still made the contestants give up. The question had the following content: 'There is a folk saying: "Don't put up a high step/Alum can be washed away with any water I use'. Using your knowledge of chemistry, please explain the above saying."

Climber Ngoc Tin could not answer this Chemistry question, leaving the opportunity to the remaining 3 contestants. However, no other contestants pressed the bell to answer the question.

Chemistry question made all 4 contestants of Road to Olympia give up.

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Lam Hoang

Source: https://vtcnews.vn/cau-hoi-hoa-hoc-khien-ca-4-thi-sinh-duong-len-dinh-olympia-chao-thua-ar934210.html