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प्रश्न
When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so?
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उत्तर
Sodium is more reactive than calcium. The reaction between sodium and water produces a large amount of heat, which causes the evolved hydrogen to burn and catch fire. But in the reaction between calcium and water, no heat is produced and hence the evolved hydrogen does not catch fire.
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संबंधित प्रश्न
Metal A has electronic configuration (2, 8, 1) and metal B has (2, 8, 8, 2). Which is more reactive? Why? Identify these metals.
Iron is
(a) More reactive than zinc
(b) More reactive than aluminium
(c) Less reactive than copper
(d) Less reactive than aluminium
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.
Write the chemical reaction when iron reacts with dilute H2SO4.
A solution of _________________ in water is green in colour.
(a) CuSO4
(b) FeSO4
(c) ZnSO4
(d) Al2(SO4)3
Explain the following reaction with the help of a balanced chemical equation:
Magnesium reacts with hot water.
Write equation for the reaction of sodium with oxygen.
Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.
With the help of examples, describe how metal oxides differ from non-metal oxides.
What type of oxides are formed when metals combine with oxygen? Explain with the help of an example.
What is the action of water on magnesium ? Write equation of the chemical reaction involved.
An element X reacts with hydrogen, when heated, to form a covalent hydride H2X. If H2X has a smell of rotten eggs, the element X is likely to be:
(a) carbon
(b) sulphur
(c) chlorine
(d) phosphorus
In nature, metal A is found in a free state while metal B is found in the form of its compounds. Which of these two will be nearer to the top of the activity series of metals?
Choose the correct alternative and rewrite the following:
Which of the following is lue in colour?
Explain the following:
Reactivity of aluminium decrease if it is dipped in nitric acid.
Arrange the following metals in the increasing order of their reactivities:
Copper, Zinc, Aluminium, and Iron
Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
Which property of metals is used for making bells and strings of musical instruments like Sitar and Violin?
Tungsten wire is used in electric bulbs.
Why is acidified water considered to be a good conductor of electricity?
