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प्रश्न
What does one mean by endothermic reaction? Give example.
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उत्तर १
Reactions in which energy is absorbed are known as endothermic reactions.
Example: \[\ce{N2(g) + O2(g) + Heat -> 2NO(g)}\]
\[\ce{2NH3(g) + Heat -> N2(g) + 3H2(g)}\]
उत्तर २
A reaction in which heat is absorbed is called an endothermic reaction.
Example: When silver chloride is left in the sunlight, it absorbs heat and turns grey because of the formation of silver metal.
\[\ce{2AgCl(s)->[Sunlight] 2Ag(s) + Cl2(g)}\]
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संबंधित प्रश्न
Write the balanced chemical equation for the following and identify the type of reaction.
\[\ce{Zinc carbonate(s) -> Zinc oxide(s) + Carbon dioxide(g)}\]
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?
Give one example of a decomposition reaction which is carried out by applying heat.
What type of reaction is represented by the following equation?
\[\ce{NH4Cl -> NH3 + HCl}\]
What is meant by a decomposition reaction?
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.
What are thermal decomposition reactions ? Explain with an example.
Identify the type of following reaction :

(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.
Give a balanced equation for –
A white precipitate obtained during a double decomposition reaction involving a silver salt with sodium salt.
Differentiate between the following:
Thermal decomposition and thermal dissociation.
Electrolysis is type of ______ reaction.
Chemical volcano is an example of ______ type of reaction.
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.
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).
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.
