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Question
Give a reason why – Addition of zinc nitrate to water is a physical change but, the addition of zinc to dilute nitric acid is a chemical change.
Solution
Zinc nitrate (soluble in water) dissolves in water and is reversible. No change in composition takes place is a physical change whereas zinc reacts with dil. nitric acid to produce H2 gas which gets oxidized to water by nitric acid (oxidizing agent) and hence is a chemical change.
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