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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.
विकल्प
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.
-
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
TRUE \ FALSE
Electrolytic refining is a method in which a thin coating of a metal is done over another metal.
Fill in the blank:
During a chemical reaction transfer of ________ takes place.
Complete the statement by filling the gap using an appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
An ______ is drawn in between the reactants and products while writing the equation for a chemical reaction.
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
Oxygen is a ______ in respiration.
Name affects the acidified K2Cr2O7 paper and also turns lime water dirty milky.
Name: A greenish-yellow gas.
Select the correct answer for the following options:
The gas which reacts with oxygen to give a neutral liquid.
Give reason for the following:
A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
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 acid to an active metal.
Give an example of a chemical reaction for the following situation:
A change in colour is observed
