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प्रश्न
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
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उत्तर
A change in which the substance can be brought back to its original state is called a reversible change.
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संबंधित प्रश्न
State whether the following statement is true or false. In case a statement is false, write the corrected statement.
Formation of manure from leaves is a physical change.
The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change − A), then it burns (Change − B). The following statements pertain to these changes. Choose the correct one.
Name three biochemical catalysts found in the human body.
TRUE \ FALSE
Positively charged electrode is called the anode. True or false ?
How is a strong electrolyte different from a weak electrolyte?
What do you observe when :
an iron nail is kept in tap water for few days
Fill in the blank:
The substances formed as a result of a chemical reaction are called _______
Explain the following reaction with one suitable example of Double decomposition reaction.
Match the pairs.
| a. | Photosynthesis | i. | Tendency to lose electrons |
| b. | Water | ii. | Reactant in combustion process |
| c. | Sodium chloride | iii. | Chemical change |
| d. | Dissolution of salt in water | iv. | Covalent bond |
| e. | Carbon | v. | Ionic bond |
| f. | Fluorine | vi. | Physical change |
| g. | Magnesium | vii. | Tendency to form anion |
Write the chemical reaction where the following changes are observed.
Colour change is noticed
Name: Two carbonates do not produce carbon dioxide on heating.
Give a chemical test to distinguish between the following gases.
H2 and O2
Give a chemical test to distinguish between the following gases.
HCl and H2S
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper nitrate to nitrogen dioxide
Circle the odd one out. Give reason for your choice
Mention the various conditions required for a chemical reaction to occur.
Analogy:
H2O: Water:: NaCl: ______.
Classify each of the following, as a physical or a chemical change. Give reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change the colour of black tea by adding lemon juice to it.
(e) Churning of milk cream to get butter.
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
Write a note on the following:
Curdling of milk
