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Question
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
Options
True
False
Solution
False
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RELATED QUESTIONS
How do the following help in bringing about a chemical change?
light.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction reaction is the exact opposite of
- displacement reaction
- decomposition reaction
- oxidation reaction
- none of these
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
Weak electrolytes dissociate partially in their aqueous or fused state.
Write true or false :
No new substance is formed during a chemical reaction.
Explain by writing a word equation.
Respiration is a chemical change.
Give an example of a reaction where the following are involved
Electricity
Give an example of a reaction where the following are involved:
Solution
Write the chemical reaction where the following changes are observed.
Gas is evolved
Multiple choice:
Thermal decomposition of sodium carbonate will produce
What do you observe? When
Barium chloride is added to sodium sulphate solution
Give an example of the following chemical changes.
A reaction where colour change is noticed.
Name: A greenish-yellow gas.
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Give a chemical test to distinguish between the following gases.
NH3 and HCl
What do you observe when CO2 is passed through lime water first and then a little in excess.
Give reason for the following:
A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
Give reason for the following:
The catalytic oxidation of sulphur dioxide to sulphur trioxide is represented by a double arrow {⇌}
between the reactants and products, formed in the chemical reaction.
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 – Thermal decomposition of mercury [II] oxide.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
On heating calcium carbonate gets converted into calcium oxide and carbon dioxide.
(a) Is this a physical or a chemical change?
(b) Can you prepare one acidic and one basic solution by using the products formed in the above process? If so, write the chemical equation involved.
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
Are these changes chemical in nature?
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
Write a word equation for the chemical change, if any.
Write a note on the following:
Curdling of milk
Write a note on the following:
Fermentation
When milk is mixed with coffee decoction, the colour of milk and decoction changes due to ______.
What are the chemical reactions that occur in everyday life?
