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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
2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.
State whether the following statement is true or false:
A chemical equation can be balanced easily by altering the formula of a reactant or product.
What does the symbol (aq) represent in a chemical equation?
Translate the following statement into a chemical equation and then balance the equation:
Barium chloride reacts with zinc sulphate to give zinc chloride and barium sulphate.
State one characteristic of the chemical reaction which takes place when quicklime is treated with water.
Write the balanced equation for the following chemical reaction.
\[\ce{Barium chloride + Aluminium sulphate -> Barium sulphate + Aluminium chloride}\]
Why do we need to balance chemical equations?
Write word equation for the following skeletal equation:
\[\ce{Ca + O2 → CaO}\]
Balance the following equation. Also name the product formed.
CO2 + C → CO
Complete the following blank in the equation as indicated.
\[\ce{CaH2_{(s)} + 2H2O_{( aq)}-> Ca(OH)2_{(s)} + 2H2_{(g)}}\]
Moles: 1 mole + ______ `→` ______ + ______
Write word equation for the following molecular equation:
\[\ce{CuSO4 + 2NaOH -> Na2SO4 + Cu(OH)2↓}\]
Word equation:
State the colour of the products.
Give a balanced equation for addition of iron to copper [II] sulphate solution. State the change in colour seen.
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:
Iron [II] sulphate to sodium hydroxide.
Give word equation for the following chemical reaction and give the names of the product formed.
\[\ce{CuO + H2SO4 -> CuSO4 + H2O}\]
Explain the term ‘chemical equation’.
CaCO3 + 2HCl[dil.] → CaCl2 + H2O + CO2 [g]
State the information provided by the above chemical equation.
Write a balanced equation for the following word equation:
Iron + Hydrochloric acid → Iron [II] chloride + Hydrogen
Write an Explanation.
Balanced equations
What is called thermolysis reactions?
A dilute ferrous sulphate solution is gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?
