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प्रश्न
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Why are decomposition reactions called the opposite of combination reactions? Explain with equations of these reactions.
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उत्तर
Decomposition reactions occur when a compound breaks up into two or more simpler substances. On the other hand, combination reactions occur when two or more substances combine to form a single substance. Thus, decomposition reactions are the opposite of combination reactions.
Decomposition Reactions:
\[\ce{CaCO3_{(s)} -> CaO_{(s)} + CO2_{(g)}}\]
\[\ce{2H2O_{(l)} ->[Electricity] 2H2_{(g)} + O2_{(g)}}\]
Combination Reactions:
\[\ce{2H2_{(g)} + O2_{(g)} -> 2H2O_{(l)}}\]
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
संबंधित प्रश्न
Write the balanced chemical equation for the following and identify the type of reaction.
\[\ce{Zinc carbonate(s) -> Zinc oxide(s) + Carbon dioxide(g)}\]
Taking into consideration the relationship in the first pair, complete the second pair
2H2 + O2 → 2H2O :Combination Reaction :: 2HgO → 2Hg + O2:_________
Rewrite the following statements by selecting the correct options:
\[\ce{CaCO3 ->[\Delta] CaO + CO2 ^}\] is a __________ reaction.
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.
- What is substance P? Write its common name as well as chemical formula.
- What is substance Q?
- What is gas R?
- What is substance S? What is its clear solution known as?
- What is substance T? Name any two natural forms in which substance T occurs in nature.
What type of reaction is represented by the following equation?
\[\ce{CaCO3 -> CaO + CO2}\]
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Thermal decomposition of a substance is brought about with the help of
- reactants
- water
- wind
- heat
How can the rate of the chemical reaction, namely, decomposition of hydrogen peroxide be increased?
Classify the following reaction into –
- Direct combination
- Decomposition
- Displacement
- Double decomposition
The reaction is – Zinc hydroxide on heating gives zinc oxide and water.
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 _________.
Photolysis is a decomposition reaction caused by ______
Electrolysis is type of ______ reaction.
Chemical volcano is an example of ______ type of reaction.
Which of the following is an endothermic process?
- 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.
Complete the following reaction:
\[\ce{C_12H_22O11->[Heat]}\] ______ + ______.
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.
