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State any two observation in which activity suggestion is occurrence of a chemical reaction |
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Answer» When a chemical reaction takes place any of these changes can be observed: ★ Change in color. ★ Change in state. ★ Evolution of gas. ★ Change in temperature. ★ Formation of precipitate. Example: ★ When LEAD nitrate and potassium iodide reacts, a yellow precipitate i.e. lead iodide is formed. ★ When sodium reacts with water, sodium HYDROXIDE is formed along with the evolution of hydrogen gas. ★ When GREEN crystals of iron oxide is heated, a successive color change is observed from green to colorless to reddish brown along with sulphur dioxide and sulphur trioxide. ★ When quicklime is mixed with water, its FORMS slaked LIME and heat is evoluted and hence there is change in temperature. |
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