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प्रश्न
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
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उत्तर
The reaction between hydrogen sulphide and chlorine (both gases) produces sulphur (solid) and hydrogen chloride (gas).
\[\ce{\underset{Hydrogen sulphide}{H2S_{(g)}} + \underset{Chlorine}{Cl2_{(g)}}-> \underset{Hydrogen chloride}{2HCl_{(g)}} + \underset{(yellow solid)}{\underset{Sulphur}{S_{(s)}}}}\]
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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.
Condensation of steam is not a chemical change.
FILL IN THE BLANK
A .............. change is a temporary change.
TRUE \ FALSE
Copper can displace iron from iron sulphate.
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
Give an example of a reaction where the following are involved
Heat
Give reason for the following:
Blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
Explain,giving one example of the following chemical changes:
Reversible reaction
Write your observation and a balanced equation in the case of the following substances being heated.
Zinc carbonate.
Name the following:
The products obtained during ‘photosynthesis’ – which is a chemical change.
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.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.
Complete the table given below.
| Heat on Zinc nitrate | Colour of residue |
State the following reaction represent oxidation or reduction.
\[\ce{Cl- ->Cl}\]
Water boiling into water vapour is an example of chemical change.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
______ are substances that speed up the process of a chemical change and it will not undergo any change during the course of the reaction.
Write the chemical reaction of baking soda with lemon.
Chemical changes are important in our day-to-day life. Give examples.
Write the characteristics of chemical change.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
