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प्रश्न
Explain the following type of chemical reaction, giving two examples for it:
Decomposition reaction
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उत्तर
A reaction in which a compound breaks up due to heat application into two or more simple substances is called a decomposition reaction.
\[\ce{AB->[heat] A + B}\]
Examples:
- Mercuric oxide when heated, decomposes to form two elements mercury and oxygen
\[\ce{2HgO_{(s)}->[heat] 2Hg_{(s)} + O2_{(g)}}\] - CaCO3 when heated decomposes to calcium oxide and carbon dioxide.
\[\ce{CaCO3 ->[heat] CaO + CO2}\]
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संबंधित प्रश्न
Why is the amount of gas collected in one of the test tubes in the following Activity double of the amount collected in the other? Name this gas.
- Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in the following Fig.
- Connect these electrodes to a 6 volt battery.
- Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
- Take two test tubes filled with water and invert them over the two carbon electrodes.
- Switch on the current and leave the apparatus undisturbed for some time.
- You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
- Is the volume of the gas collected the same in both the test tubes?
• Once the test tubes are filled with the respective gases, remove them carefully. - Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.
Caution: This step must be performed carefully by the teacher.
- What happens in each case?
- Which gas is present in each test tube?
What does one mean by exothermic reaction? Give example.
What type of reaction is represented by the digestion of food in our body?
What type of chemical reaction is represented by the following equation?
\[\ce{X -> Y + Z}\]
What is the colour of ferrous sulphate crystals? How does this colour change after heating?
Two metals X and Y form the salts XSO4 and Y2SO4, respectively. The solution of salt XSO4 is blue in colour whereas that of Y2SO4 is colourless. When barium chloride solution is added to XSO4 solution, then a white precipitate Z is formed along with a salt which turns the solution green. And when barium chloride solution is added to Y2SO4 solution, then the same white precipitate Z is formed along with colourless common salt solution.
- What could the metals X and Y be?
- Write the name and formula of salt XSO4.
- Write the name and formula of salt Y2SO4.
- What is the name and formula of white precipitate Z?
- Write the name and formula of the salt which turns the solution green in the first case.
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{Zn_{(s)} + H2SO4 -> ZnSO4_{(s)} + H2_{(g)}}\]
Differentiate between the following:
Electrolytic decomposition and photochemical decomposition.
Chemical volcano is an example of ______ type of reaction.
Assertion: Decomposition of vegetable matter into compost is an endothermic reaction.
Reason: Decomposition reaction involves breakdown of a single reactant into simpler products.
