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Questions
What is a decomposition reaction?
What is meant by decomposition reaction?
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Solution
A decomposition reaction is a chemical reaction in which a single compound breaks down to simpler products. It is the opposite of a combination reaction.
RELATED QUESTIONS
Write the balanced chemical equation for the following and identify the type of reaction.
\[\ce{Zinc carbonate(s) -> Zinc oxide(s) + Carbon dioxide(g)}\]
What does one mean by exothermic reaction? Give example.
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
A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.
(a) What is substance P? Write its common name as well as chemical formula.
(b) What is substance Q?
(c) What is gas R?
(d) What is substance S? What is its clear solution known as?
(e) What is substance T? Name any two natural forms in which substance T occurs in nature.
The white solid compound A decomposes quite rapidly on heating in the presence of a black substance X to form a solid compound B and a gas C. When an aqueous solution of compound B is reacted with silver nitrate solution, then a white precipitate of silver chloride is obtained along with potassium nitrate solution. Gas C does not burn itself but helps burn other things.
(a) What is compound A?
(b) What is compound B?
(c) What is gas C?
(d) What do you think is the black substance X? What is its function?
(e) What is the general name of substances like X?
Give one example of a decomposition reaction which is carried out by applying heat.
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 reaction is represented by the following equation?
2 FeSO4 → Fe2 O3 + SO2 + SO3
What type of reaction is represented by the following equation?
NH4 CI → NH3 + HCI
What type of reaction is represented by the following equation?
NH4NO2 → N2 + 2H2O
State the change in colour observed in following case mentioning the reason:
Silver chloride is exposed to sunlight.
Which of the following can be decomposed by the action of light?
(a) NaCl
(b) KCl
(c) AgCl
(d) CuCl
A metal salt MX when exposed to light splits up to form metal M and a gas X2. Metal M is used in making ornaments whereas gas X2 is used in making bleaching powder. The salt MX is itself used in black and white photography.
(a) What do you think metal M is?
(b) What could be gas X2?
(c) Name the metal salt MX.
(d) Name any two salt solutions which on mixing together can produce a precipitate of salt MX.
(e) What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of the reaction?
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{Zn_{(s)} + H2SO4 -> ZnSO4_{(s)} + H2_{(g)}}\]
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 :
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) Design an activity to demonstrate the decomposition reaction of lead nitrate.
(b) Draw labelled diagram of the experimental set-up. List two main observations.
(c) Write balanced chemical equation for the reaction stating the physical state of the reactant and the products.
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.
Classify the following reaction into different type:
\[\ce{2KClO3(s)->[\Delta] 2KCl(aq) + 3O2(g)}\]
Give a balanced equation for –
An electrolytic decomposition reaction involving a neutral liquid
Give a balanced equation for –
A double decomposition neutralization reaction involving an acid and a base
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 _________.
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.
Give a balanced equation for the following type of reaction:
A thermal decomposition reaction in which a compound decomposes to give two new compounds.
Differentiate between the following:
Electrolytic decomposition and photochemical decomposition.
What is electrolysis?
Explain the reaction given in the figure.
Photolysis is a decomposition reaction caused by ______
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?
Which one of the following processes involves chemical reactions?
Give the ratio in which hydrogen and oxygen are present in water by volume.
When SO2 gas is passed through a saturated solution of H2S, which of the following reaction occurs?
Assertion: Decomposition of vegetable matter into compost is an endothermic reaction.
Reason: Decomposition reaction involves breakdown of a single reactant into simpler products.
Balance the following chemical equation and identify the type of chemical reaction.
`"HgO"("s") overset("(heat)")(->) "Hg"("l") + "O"_2("g")`
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.
A metal nitrate 'A' on heating gives a metal oxide along with evolution of a brown coloured gas 'B' and a colourless gas, which helps in burning. Aqueous solution of 'A' when reacted with potassium iodide forms a yellow precipitate.
- Identify 'A' and 'B'
- Name the types of the reactions involved in the above statement.
What is observed when silver chloride is exposed to sunlight? Give the type of reaction involved.
