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प्रश्न
(a) What is double displacement reaction? Explain with an example.
(b) A small amount of quick lime is added to water in a beaker.
(i) Name and define the type of reaction that has taken place.
(ii) Write balanced chemical equation for the above reaction and the chemical name of the product formed.
(iii) List two main observations of this reaction.
उत्तर
(a) Double Displacement Reaction : Reactions in which there is an exchange of ions between the reactants are called Double Displacement Reactions.
Example : \[\ce{Pb(NO3)2_{(aq)} + 2KI_{(aq)} -> \underset {\text{(Yellow ppt)}}{PbI_2}( v) + 2KNO3_{(aq)} }\]
(b) (i) Reaction taking place is combination reaction. A reaction in which two or more reactants combine to form a single product is known as combination reaction.
\[\ce{\underset{\text{Quick lime}}{CaO_{(s)}} + H2O_{(l)} -> \underset{\text{(Calcium hydroxide)}}{Ca(OH)2_{(aq)}} + Heat}\]
(iii) Two main observations :Calcium oxide when reacts vigorously with water produces slaked lime i.e Ca(OH)2 . A large amount of heat is evolved . This is an Exothermic reaction .
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संबंधित प्रश्न
What type of reaction is represented by the following equation?
2 Ca + O2 → 2CaO
What type of chemical reaction take place when a magnesium wire is burnt in air?
What type of chemical reaction is represented by the following equation?
A + B → C
Give one example each of which illustrates the following characteristics of a chemical reaction:
change of colour
Fill in the blank
A reaction in which two or more substances combine to form a single substance is called a ............ reaction.
Explain the following type of chemical reaction, giving two examples for it:
Combination reaction
Calcium oxide reacts vigorously with water to produce slaked lime.
\[\ce{CaO{(s)} + H2O(l) -> Ca(OH)2(aq)}\]
This reaction can be classified as:
(A) Combination reaction
(B) Exothermic reaction
(C) Endothermic reaction
(D) Oxidation reaction
Classify the following reaction into –
- Direct combination
- Decomposition
- Displacement
- Double decomposition
The reaction is – Molten zinc at high temperatures, burns in air to give zinc oxide.
Read the text below and answer the questions that follow:
A small amount of hydrochloric acid was taken in a test tube. The test tube was heated. A glass rod was dipped in the ammonia solution and held on the top of the test tube. A white smoke was seen emanating from the tip of the glass rod.
- What must have happened?
- Which colour of gas is formed?
- Write the chemical equation for the reaction.
A clear solution of slaked lime is made by dissolving Ca(OH)2 in an excess of water. This solution is left exposed to air. The solution slowly goes milky as a faint white precipitate forms. Explain why a faint white precipitate forms, support your response with the help of a chemical equation.
