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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.
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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
What is a balanced chemical equation? Why should a chemical equation be balanced?
Write the balanced chemical equation for the following reaction.
\[\ce{Zinc + Silver nitrate -> Zinc nitrate + Silver}\]
Write word equation for the following skeletal equation:
\[\ce{FeCl2 + Cl2 -> FeCl3}\]
Write word equation for the following skeletal equation:
\[\ce{Ca + O2 → CaO}\]
Balance the following chemical equation :
Na2CO3 + HCl → NaCI + H2O + CO2
Write your observation for the following chemical reaction and name the product formed :
When ammonium chloride is heated with sodium hydroxide.
Write your observation for the following chemical reaction and name the product formed :
When water is added to quick lime?
Balance the following equation. Also name the products formed.
`"Mg" + "O"_2 → "MgO"`
Balance the following equation:
S + H2SO4 → SO2 + H2O
Balance the following equation:
NaHCO3 → Na2CO3 + H2O + CO2
Write the balanced chemical equation of the following reaction.
barium chloride + sulphuric acid → barium sulphate + hydrochloric acid
\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
0.02 moles of pure MnO2 is heated strongly with conc. HCl. Calculate mass of MnO2 used.
Give word equation for the following chemical reaction and give the names of the product formed.
ZnCO3 → ZnO + CO2
Give reason for the following:
Silver salts are kept in dark coloured bottles.
Give an example of a chemical equation in which two reactants form:
two product
Balance the following simple equation:
Al + H2O → Al2O3 + H2
Write a balanced equation for the following word equation:
Calcium hydroxide + Ammonium chloride → Calcium chloride + Water + Ammonia
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
CaC2 + N2 → 2CaCN2 + C
Writing a chemical reaction in brief by using chemical formulae is called as _______.
Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of NaOH, anhydrous CuSO4 and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is(are) correct?
- In beakers A and B, exothermic process has occurred.
- In beakers A and B, endothermic process has occurred.
- In beaker C exothermic process has occurred.
- In beaker C endothermic process has occurred.
