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प्रश्न
Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.
उत्तर १
Some metals, when exposed to air for a long time, react with oxygen in the atmosphere to form a dull layer of metal oxide on their surfaces. This makes the metals look dull.
उत्तर २
Most of the metals are reactive towards air. They react with oxygen present in the air to form metal oxides. The metal oxide formation appears on the surface of the metals as a thin layer. This thin layer formation of metal oxide on the metallic surface causes the dull appearance of the metals. Thus, the surface of some metals acquires a dull appearance when exposed to air for a long time.
संबंधित प्रश्न
A solution of _________________ in water is green in colour.
(a) CuSO4
(b) FeSO4
(c) ZnSO4
(d) Al2(SO4)3
What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails dipped in copper sulphate solution for about 30 minutes?
Fill in the following blank with suitable word:
Ordinary aluminium strips are not attacked by water because of the presence of a layer of ................. on the surface of aluminium.
What type of oxides are formed when non-metals react with oxygen? Explain with an example.
Name two metals which can, however, liberate hydrogen gas from very dilute nitric acid.
What is the action of water on aluminium ? Write equation of the chemical reaction involved.
Write the equation for the reaction of Iron with dilute hydrochloric acid.
Name the products formed. Also indicate the physical states of all the substances involved.
You are given a solution of AgNO3. Which of the following do you think cannot displace Ag from AgNO3solution?
(a) Magnesium
(b) Zinc
(c) Gold
(d) Copper
An element E reacts with water to form a solution which turns phenolphthalein solution pink. The element E is most likely to be:
(a) S
(b) Ca
(c) C
(d) Ag
An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.
