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Question
Name the elements water is made of. What are the valencies of these elements ? Work out the chemical
formula for water.
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Solution
Water (H2O) is made of Hydrogen and Oxygen.
Valency of Hydrogen is 1, and valency of Oxygen is 2.
Valency of one Hydrogen atom = 1
Valency of one Oxygen atom = 2
Therefore, to balance the valency of Oxygen atom, 2 atoms of Hydrogen atoms are required.
Hence, 2 atoms of Hydrogen will combine with 1 atom of Oxygen to form one molecule of water with the chemical formula H2O.
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