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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:
- Evolution of a gas
- 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 that heat is evolved during the reaction. That is, a change in temperature.
\[\ce{Zn + H2SO4 -> ZnSO4 + H2\uparrow + Heat}\]
संबंधित प्रश्न
Translate the following statement into a chemical equation and then balance it.
Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
How will you indicate the following effect in a chemical equation?
Endothermic reaction
Convey the following information in the form of a balanced chemical equation:
“An aqueous solution of ferrous sulphate reacts with an aqueous solution of sodium hydroxide to form a precipitate of ferrous hydroxide and sodium sulphate remains in solution.”
When potassium nitrate is heated, it decomposes into potassium nitrite and oxygen. Write a balanced equation for this reaction and add the state symbols of the reactants and products.
Give one example of an exothermic reaction.
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When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
(a) What could be solid X? Write its chemical formula.
(b) What could be product Y? Write its chemical formula.
(c) What is the common name of the solution of Y which is used for testing carbon dioxide gas?
(d) Write chemical equation of the reaction which takes place on adding water to slid X.
(e) Which characteristic of chemical reactions is illustrated by this example?
Write your observation for the following chemical reaction and name the product formed :
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\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
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\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
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Write the balanced chemical equation for this reaction.
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\[\ce{2H2O ->[electric][current] 2H2 + O2}\]
Balance the following simple equation:
\[\ce{Ca(OH)2 + HNO3 -> Ca(NO3)2 + H2O}\]
Write a balanced equation for the following word equation:
Nitrogen dioxide + Water + Oxygen → Nitric acid
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
PbO2 +4HCl → PbCl2 + H2O + Cl2
In the chemical equation the _______ are written on the left-hand side.
To balance the following chemical equation the value of x and y should respectively be:
\[\ce{2NaOH + xAl_2O_3->yNaAlO_2 + H_2O}\]
