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    Answer 5 out of 6 questions correctly.

Water is one of the few compounds found in liquid state on Earth's surface. Water is an essential component of all living things. In fact, the human body is about
60%
water! Water's chemical structure and properties play a key role in sustaining life on Earth.
two cupped hands with water flowing from the hands into a lake
Water is made of two chemical elements: oxygen and hydrogen. The element oxygen is a colorless, odorless gas that makes up about 
21%
 of our atmosphere. Most living things need oxygen to survive. The element hydrogen is also a colorless, odorless gas. Pure hydrogen is highly flammable and can explode in air!
When an oxygen atom bonds to two hydrogen atoms, 
H
2
O
, or water, is formed. Water is a colorless, odorless liquid at room temperature.
Select the true statements.
ref_doc_title.

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