Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.
The surface of some metal acquires a dull appearance because metals form a thin layer of oxides, carbonates or sulphides on their surface when exposed to air for a long time.
Related Articles (a) Give reason why copper is used to make hot water tanks but steel (an alloy of iron) is not.(b) Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.
Some metals lose their lustre when exposed in the air. Why?
What happens when a copper vessel is exposed to moist air for a long time?
When a vessel is exposed to moist air for a long time, then a green coating is formed on its surface. The vessel must be made of:zincmagnesiumironcopper
When a copper object is exposed to moist air for a long time, then a green coating is formed on its surface.(a) What is the material of the green coating?(b) State whether the green coating is acidic or basic.
The cut surface of a Brinjal which has been exposed to air turns brown due to?
When Ag is exposed to air it gets a black coating of
Explain why, a land plant may die if its roots remain waterlogged for a long time.
Metals have lustre (shine). Give reason why some metal articles become dull and loose their shine.
A balloon when kept in sun, bursts after some time. Why?
(a) Why is an iron grill painted frequently?(b) Explain why, though aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
lt was Paheli’s birthday. Her grandmother gave her two gifts made of metals, one old dull silver spoon and a pair of lustrous gold earrings. She was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference?
You might have noticed that when used for a long time, slippers with rubber soles become slippery. Explain the reason.
Explain why, when air is taken in and let out during breathing, the lungs always contain a residual volume of air.
(a) Name an alloy of copper. State its chemical composition and any one use.(b) Explain why, when a copper object remains in damp air for a considerable time, a green coating is formed on its surface. What is this process known as ?
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