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प्रश्न
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?
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उत्तर
Yes, the changes are chemical changes because new substances iron sulphate (green) and copper (brown) are formed in the reaction.
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संबंधित प्रश्न
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
FILL IN THE BLANK
In a double decomposition precipitation reaction both the reactants must be ............ soluble.
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
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CO2 and SO2
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- 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.
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Circle the odd one out. Give reason for your choice
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A very hot glass on putting in cold water cracks. What does this change indicate?
Match the following:
| Column I | Column II | ||
| 1. | Burning of coal | a. | Rusting |
| 2. | Painting of a surface | b. | Evaporation |
| 3. | Dipping iron in the water | c. | Chemical change |
| 4. | Salt from seawater | d. | Prevention of rusting |
Photosynthesis is a chemical charge. Justify your answer.
