Advertisements
Advertisements
प्रश्न
Ordinary aluminium strips are not attacked by water because of the presence of a layer of ______ on the surface of aluminium.
Advertisements
उत्तर
Ordinary aluminium strips are not attacked by water because of the presence of a layer of aluminium oxide on the surface of aluminium.
Explanation:
Aluminium is a highly reactive metal that instantly reacts with oxygen in the air to form a thin, tough, and impervious layer of aluminium oxide. This stable oxide film adheres tightly to the metal surface, acting as a protective barrier that prevents water or oxygen from penetrating deeper into the underlying metal. Because of this self-passivating property, ordinary aluminium strips remain unattacked by water under normal conditions. The protective layer is chemically represented as Al2O3.
APPEARS IN
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.
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.
Food cans are coated with tin and not with zinc because ______.
From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal:
- which reacts with water only on boiling, and
- another which does not react even with steam.
With the help of examples, describe how metal oxides differ from non-metal oxides.
How do metals react with hydrogen? Explain with an example.
What happens when magnesium reacts with very dilute nitric acid? Write an equation for the reaction involved.
Why does aluminium not react with water under ordinary conditions?
Why is white phosphorus kept immersed under water?
Describe the reaction of potassium with water. Write the equation of the reaction involved.
What is the action of water on sodium ? Write equation of the chemical reaction involved.
Hydrogen is not a metal but still it has been assigned a place in the reactivity series of metals. Why?
An element X forms two oxides XO and XO2. The oxide XO is neutral but XO2 is acidic in nature. The element X is most likely to be:
(a) sulphur
(b) carbon
(c) calcium
(d) hydrogen
Zinc oxide is a metal oxide. Which of the following term best describes the nature of zinc oxide:
(a) an acidic oxide
(b) a basic oxide
(c) an amphoteric oxide
(d) a neutral oxide
Metal A burns in air, on heating, to form an oxide A2O3 whereas another metal B burns in air only on strong heating to form an oxide BO. The two oxides A2O3 and BO can react with hydrochloric acid as well as sodium hydroxide solution to form the corresponding salts and water.
(a) What is the nature of oxide A2O3?
(b) What is the nature of oxide BO?
(c) Name one metal like A.
(b) Name one metal like B.
Which of the following reactions will not occur? Why not?
(a) MgSO4 (aq) + Cu (s) → CuSO4 (aq) + Mg (s)
(b) CuSO4 (aq) + Fe (s) → FeSO4 (aq) + Cu (s)
(c) MgSO4 (aq) + Fe (s) → FeSO4 (aq) + Mg (s)
Name a metal which It does not react with any physical state of water?
Write the chemical equation of the above process.
Explain the following:
Reactivity of aluminium decrease if it is dipped in nitric acid.
