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प्रश्न
विकल्प
Fe + S ⟶ FeS.
HCl + NaOH ⟶ NaCl + H2O
CuSO4 + Zn ⟶ ZnSO4 + Cu
\[\ce{CaCO3 ->[\Delta]CaO + CO2}\]
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उत्तर
\[\ce{CaCO3 ->[\Delta]CaO + CO2}\] is a decomposition reaction.
APPEARS IN
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?

Write one equation for decomposition reactions where energy is supplied in the form of heat.
Taking into consideration the relationship in the first pair, complete the second pair
2H2 + O2 → 2H2O :Combination Reaction :: 2HgO → 2Hg + O2:_________
What type of reaction is represented by the following equation?
\[\ce{CaCO3 -> CaO + CO2}\]
What type of chemical reaction takes place when limestone is heated?
What type of reaction is represented by the following equation?
\[\ce{NH4NO2 -> N2 + 2H2O}\]
Name the product formed on strongly heating ferrous sulphate crystals. What type of chemical reaction occurs in this change?
What is meant by a decomposition reaction?
State the change in colour observed in the following case, mentioning the reason:
Silver chloride is exposed to sunlight.
Which of the following can be decomposed by the action of light?
Explain the following type of chemical reaction, giving two examples for it:
Decomposition reaction
How will you obtain Nitrogen dioxide from lead nitrate.
Also give balanced equations for the reactions
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Thermal decomposition of a substance is brought about with the help of
- reactants
- water
- wind
- heat
What are thermal decomposition reactions ? Explain with an example.
What is a redox reaction? Explain with an example.
What does one mean by endothermic reaction? Give example.
Study the following figure and answer questions.

a) After heating Calcium carbonate, which gas is formed in a test tube?
b) When we pass this gas through limewater what change, did you observe?
c) Write down the chemical reaction showing the product formation after heating the Calcium carbonate.
A student wants to study a decomposition reaction by taking ferrous sulphate crystals. Write two precautions he must observe while performing the experiment.
How can the rate of the chemical reaction, namely, decomposition of hydrogen peroxide be increased?
Answer the following question.
2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reaction.
Give a balanced equation for –
An electrolytic decomposition reaction involving a neutral liquid
Complete the statement by filling in the blank with the correct word:
Decomposition of silver salts in the presence of sunlight is an example of _________.
Give a balanced equation for the following type of reaction:
A thermal decomposition reaction in which a metallic nitrate decomposes to give – a basic oxide.
Differentiate between the following:
Thermal decomposition and thermal dissociation.
Chemical volcano is an example of ______ type of reaction.
Which one of the following processes involves chemical reactions?
Give the ratio in which hydrogen and oxygen are present in water by volume.
Which of the following is an endothermic process?
When SO2 gas is passed through a saturated solution of H2S, which of the following reaction occurs?
On heating blue coloured powder of copper (II) nitrate, in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed
- Write a balanced chemical equation of the reaction.
- Identify the brown gas X evolved.
- Identify the type of reaction.
- What could be the pH range of aqueous solution of the gas X?
The reaction of calcium carbonate, with freshly prepared lime water, is shown below:
Answer the questions with the help of a diagram:
- What type of reaction does calcium carbonate undergoes?
- What change in colour is observed in lime?
- Write the chemical equation.

These consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
Assertion: Silver bromide decomposition is used in black and white photography.
Reason: Light provides energy for this exothermic reaction.

- Identify the gasses evolved at the anode and cathode in the above experimental set up.
- Name the process that occurs. Why is it called so?
- Illustrate the reaction of the process with the help of a chemical equation.
Write one equation for the decomposition reaction where energy is supplied in the form of light.
A solution of a substance ‘X’ is used for whitewashing.
- Name the substance ‘X’ and write its formula.
- Write the reaction of the substance ‘X’ named in the above formula with water.
