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प्रश्न
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
पर्याय
True
False
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उत्तर
This statement is True.
Explanation:
When a candle burns, both physical and chemical changes occur:
-
Physical Change: The wax of the candle melts due to the heat of the flame. This is a reversible change as the wax can solidify again when cooled.
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Chemical Change: The wax undergoes combustion, reacting with oxygen in the air to form carbon dioxide and water vapour. This is an irreversible chemical reaction.
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संबंधित प्रश्न
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
MATCH THE COLUMNS
| 1 . `H_2` + `CI_2` `→` 2HCI | a. displacement reaction |
| 2. `2FeCI_3`+ `H_2` `→` `2FeCI_2` +2HCI` | b. addition of an electronegative redical |
| 3. Fe + `CuSO_4` `→``FeSO_4` +Cu` | c. removal of an electronegative redical |
| 4. `2H_2O` +`4NO_2`+`O_2` `→` `4HNO_3` | d.reduction by adding hydrogen |
| 5. 3Fe +`3CI_2` `→` `2FeCI_3` | e.electrolysis of water |
| 6. `FeCI_3`+ 3NaOH `→``Fe(OH)_3``↓`+NaCI | F.double decomposition,precipitation reaction |
| 7.`2H_2O` `→` `2H_2``↑`+`O_2` | e. combination or synthesis reaction |
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Potassium fluoride
Give an example of a reaction where the following are involved
Heat
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
The chemical change is ______.
Heat may evolve or be absorbed during a ______ change.
______ are substances that speed up the process of a chemical change and it will not undergo any change during the course of the reaction.
Write a note on the following:
Fermentation
What is the difference between reactants and products?
