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प्रश्न
Give reason for the following:
Electrolytic decomposition of water is a reaction involving change of state.
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उत्तर
Electrolysis of water is the decomposition of water into hydrogen and oxygen due to the passage of electric current through it.
\[\ce{2H2O(l)->[Electric Current] 2H2 (g) + O2 (g)}\]
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संबंधित प्रश्न
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
What do you observe when iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Miscible liquids having slightly different boiling points can be separated by the
- evaporation
- distillation
- fractional distillation
- sedimentation
FILL IN THE BLANK
On reaction with sulphuric acid solution, barium chloride forms a white precipitate of ........ sulphate.
FILL IN THE BLANK
In a ............ change, new substances are formed.
Fill in the blank:
The substances formed as a result of a chemical reaction are called _______
Copper carbonate when heated, it turns :
| Reactants | Products | Type of chemical reaction |
| BaCl2(aq) + ZnSO4(aq) | H2CO3(aq) | Displacement |
| 2AgCl(s) | FeSO4(aq) + Cu(s) | Combination |
| CuSO4(aq) + Fe(s) | BaSO4↓ + ZnCl2(aq) | Decomposition |
| H2O(l) + CO2(g) | 2Ag(s) + Cl2(g) | Double displacement |
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Hydrogen chloride
Explain,giving one example of the following chemical changes:
Reversible reaction
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
Complete and balance the following reaction:
\[\ce{CuCO3 ->[\Delta]}\]
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of dilute hydrochloric acid to silver nitrate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
Complete the table given below.
| Heat on ammonium dichromate | Name of neutral gas evolved |
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
Classify the following processes into physical or chemical changes:
- Beating of aluminium metal to make aluminium foil.
- Digestion of food.
- Cutting of a log of wood into pieces.
- Burning of crackers.
Beating an egg to make a cake is a ______.
Heat may evolve or be absorbed during a ______ change.
