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प्रश्न
Fill in the blank:
The substances which undergo chemical change are called _______
उत्तर
The substances which undergo chemical change are called reactants .
APPEARS IN
संबंधित प्रश्न
How would you show that setting of curd is a chemical change?
Complete and balance the following chemical equations:
\[\ce{Pb(NO3)2->[heat]}\] _________
FILL IN THE BLANK
A .............. change is a temporary change.
FILL IN THE BLANK
Negatively charged ions are called ..........
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 |
TRUE \ FALSE
Ammonia is a good oxidizing agent.
Define chemical reaction.
Balance the following equation :
Fe + H2O → Fe3O4 + H2
State what you would observe when the following substance is heated in a glass test tube red lead.
Name the type of chemical reaction shown by the following equation:
2Mg + O2 → 2MgO
Out of sodium and sulphur which is a metal? Explain its reaction with the oxygen.
Explain by writing a word equation.
Respiration is a chemical change.
Define Photochemical reaction
Give an example
State the original colour of the following substance and colour of residue obtained after heating.
Lead nitrate
Give a chemical test to distinguish between the following gases.
HCl and H2S
Write your observation and a balanced equation in the case of the following substances being heated.
Copper nitrate.
Select the correct answer for the following options:
The pale blue precipitated obtained when copper [II] sulphate reacts with sodium hydroxide.
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 balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
True or False. If false, give the correct answer.
Taking a glass of water and freezing it by placing it in the freezer is a chemical change.
Mention the various conditions required for a chemical reaction to occur.
The percentage composition of Nitrogen in Ureas is ______.
What is the use of indicator?
Arrange the following statements in correct sequence:
- One side is water-loving and other water-hating molecules.
- When you agitate the cloth, the dirt is surrounded by many molecules and taken away from the cloth.
- The dirt surrounded by the detergent molecules floats in the water making it dirty.
- Finally, the cloth is clean.
- The detergent molecules have two sides.
- Water hating goes and joins with dirt and oil in the cloth while the water-loving joins with the water molecules.
Give an example of a chemical reaction for each of the following situations:
A change in colour is observed.
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 the formation of rust from iron is a chemical change?
Write the chemical reaction of baking soda with lemon.
The reaction of H2 gas with oxygen gas to form water is an example of ______.
When milk is mixed with coffee decoction, the colour of milk and decoction changes due to ______.
