Advertisements
Advertisements
Question
Rewrite the following statements by selecting the correct options:
\[\ce{CaCO3 ->[\Delta] CaO + CO2 ^}\] is a __________ reaction.
Options
combination
displacement
double displacement
decomposition
Advertisements
Solution
Decomposition
In decomposition reactions, one compound breaks down (or decomposes) to form two or more products. When calcium carbonate is heated, it forms calcium oxide and releases carbon dioxide.
APPEARS IN
RELATED QUESTIONS
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.
Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity
What type of reaction is represented by the digestion of food in our body?
State an important use of decomposition reactions.
Give one example of a decomposition reaction which is carried out with electricity
What type of reaction is represented by the following equation?
\[\ce{CaCO3 -> CaCO + CO2}\]
What type of chemical reaction takes place when silver bromide is exposed to sunlight?
What type of chemical reaction takes place when electricity is passed through water?
What type of chemical reaction is represented by the following equation?
\[\ce{X -> Y + Z}\]
What type of reaction is represented by the following equation?
\[\ce{NH4NO2 -> N2 + 2H2O}\]
What is the colour of ferrous sulphate crystals? How does this colour change after heating?
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.
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 does one mean by endothermic reaction? Give example.
Identify the type of following reaction :

A student wants to study a decomposition reaction by taking ferrous sulphate crystals. Write two precautions he must observe while performing the experiment.
Give a balanced equation for –
A thermal decomposition reaction involving heat on limestone [calcium carbonate]
Give a balanced equation for –
A white precipitate obtained during a double decomposition reaction involving a silver salt with sodium salt.
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 _________.
The chemical reaction in which two or more products are formed from a single reactant is called ______ reaction.
Explain the reaction given in the figure.

The following reaction is used for the preparation of oxygen gas in the laboratory:
\[\ce{2KClO3_{(s)} ->[Heat] 2KCl + 3O2_{(g)}}\]
Which of the following statement about the reaction is correct?
Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:
Which one of the following processes involves chemical reactions?
Balance the following chemical equation and identify the type of chemical reaction.
`"HgO"("s") overset("(heat)")(->) "Hg"("l") + "O"_2("g")`
Balance the following chemical equation and identify the type of chemical reaction.
`"H"_2"O"_2("l") overset("U V")(->) "H"_2"O"("l") + "O"_2("g")`
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?
What is observed when silver chloride is exposed to sunlight? Give the type of reaction involved.
When lead nitrate is heated strongly in a boiling tube, two gases are liberated and a solid residue is left behind in the test tube.
- Name the type of chemical reaction and define it.
- Write the name and formula of the coloured gas liberated.
- Write the balanced chemical equation for the reaction.
- Name the residue left in the test tube and state the method of testing its nature (acidic/basic).
Write the molecular formula of calcium carbonate.
Write one equation for the decomposition reaction where energy is supplied in the form of electricity.
