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प्रश्न
Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.
उत्तर
Two observations that may suggest that a chemical reaction has taken place are
(i) evolution of a gas and
(ii) change in temperature.
For example, zinc granules react with dilute sulphuric acid to evolve hydrogen gas, which is easily observed by the bubbles of hydrogen gas appearing around zinc granules. Also, the flask becomes hot, which shows heat is evolved during the reaction—that is, change in temperature.
Zn + H2SO4 → ZnSO4 + H2↑ + Heat
संबंधित प्रश्न
Write the balanced chemical equation for the following reaction.
\[\ce{Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water}\]
Balance the following equation:
Na + O2 
Na2O
Is Decomposition of calcium carbonate an endothermic reaction or an exothermic reaction?
Balance the following chemical equation:
Write your observation and name the product when ron nails are added to an aqueous solution of copper sulphate.
What do the following symbol stand for?
2H2
What information does the following chemical equation convey?
Zn + H2SO4 → ZnSO4+ H2
In certain reaction an insoluble solid called precipitate is formed. State the colour and name of the precipitate formed in the following reaction involving addition of:
Lead nitrate to ammonium hydroxide.?
Balance the following simple equation:
K + CO2 → K2O + C
Balance the following simple equation:
\[\ce{Ca(OH)2 + HNO3 -> Ca(NO3)2 + H2O}\]
