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प्रश्न
You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
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उत्तर
Copper reacts with moist carbon dioxide in the air to form copper carbonate, which causes a copper vessel to lose its shiny brown surface and form a green layer of copper carbonate. The citric acid present in lemon or tamarind neutralises the base copper carbonate and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface its characteristic lustre.
\[\ce{2Cu + \underset{(Present in air)}{H2O + CO2 + O2} -> \underset{(green)}{\underset{Basic copper carbonate}{CuCO3.CU(OH)2}}}\]
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संबंधित प्रश्न
Name the following:
Metals which forms an amphoteric oxide.
‘E’ is an element which reacts with oxygen to form an oxide E2O. An aqueous solution of E2O turns red litmus blue, so:
i. What is the nature of oxide E2O ?
ii. Write the name of element ‘E’.
Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
| Metal | Iron (II) sulphate | Cooper (II) sulphate | Zinc sulphate | Silver nitrate |
| A | No reaction | Displacement | ||
| B | Displacement | No reaction | ||
| C | No reaction | No reaction | No reaction | Displacement |
| D | No reaction | No reaction | No reaction | No reaction |
Use the Table above to answer the following questions about metals A, B, C and D.
- Which is the most reactive metal?
- What would you observe if B is added to a solution of copper (II) sulphate?
- Arrange the metals A, B, C and D in the order of decreasing reactivity.
Explain the following reaction with the help of a balanced chemical equation:
Magnesium reacts with hot water.
Name the metal which has been placed at the bottom of the reactivity series.
Name the metal which has been placed at the top of the reactivity series.
Name the metal which has been placed just below copper in the reactivity series.
Write an equation for the reaction of:
Magnesium with oxygen
How would you show that silver is chemically less reactive than copper?
The white powder formed when magnesium ribbon burns in oxygen is of ______.
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Why is white phosphorus kept immersed under water?
Which gas is produced when dilute hydrochloric acid is added to a reactive metal?
Write the equation for the reaction of:
Magnesium with dilute hydrochloric acid.
Name the products formed in the given case. Also indicate the physical states of all the substances involved.
Write the equation for the reaction of:
Aluminium with dilute hydrochloric acid.
Name the products formed in the given case. Also indicate the physical states of all the substances involved.
The least reactive metal among the following is:
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Choose the correct alternative and rewrite the following:
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Rewrite the following statement by selecting the correct option.
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