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प्रश्न
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
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उत्तर
A catalyst either increases or decreases the rate of a chemical change but itself remains unchanged at the end of the reaction.
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संबंधित प्रश्न
Define precipitation reaction.
FILL IN THE BLANK
Negatively charged ions are called ..........
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
Fill in the blank:
During a chemical reaction transfer of ________ takes place.
Write true or false :
No new substance is formed during a chemical reaction.
Balance the following equation :
Fe + H2O → Fe3O4 + H2
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)
Rusting of iron is a ______ chemical change.
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Give an example of a reaction where the following are involved
Light
Write the chemical reaction where the following changes are observed.
Gas is evolved
State the original colour of the following substance and colour of residue obtained after heating.
Copper carbonate
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
Write your observation and a balanced equation in the case of the following substances being heated.
Copper carbonate.
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 water to quicklime.
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
______ is the chemical name of slaked lime.
