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प्रश्न
Fill in the blank:
In some chemical reactions an insoluble ________ is formed when two solutions are mixed.
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उत्तर
In some chemical reactions an insoluble precipitate is formed when two solutions are mixed.
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संबंधित प्रश्न
Complete and balance the following chemical equations:
N2 + O2 →
Give reason.
Acidic soil is treated with quick lime.
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
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 |
What do you observe when :
an iron nail is kept in tap water for few days
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Explain by writing a word equation.
Bubbles are seen on adding lemon juice to baking soda.
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 |
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
Give an example of the following chemical changes.
A reaction where colour change is noticed.
Complete and balance the following reaction:
NaCl(aq) + AgNO3(aq) →
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
What do you observe when CO2 is passed through lime water first and then a little in excess.
Select the correct answer for the following options:
The gas obtained when potassium chlorate is heated in the presence of a catalyst.
Mention the various conditions required for a chemical reaction to occur.
Water boiling into water vapour is an example of chemical change.
Give two examples for the following case:
Chemical changes
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think formation of rust from iron is a chemical change?
Which is used as a catalyst during the process of hydrogenation of oils?
