Advertisements
Advertisements
प्रश्न
A metal X which is resistant to corrosion is produced by the electrolysis of its molten oxide whereas another metal Y which is also resistant to corrosion is produced by the reduction of its oxide with carbon. Metal X can be used in powder form in thermite welding whereas metal Y is used in making cathodes of ordinary dry cells.
(a) Name the metals X and Y.
(b) Which of the two metals is more reactive : X or Y?
(c) Name one ore or metal X. Also write its chemical formula.
(d) Name one ore or metal Y. Also write its chemical formula.
(e) Name one alloy of metal X and one alloy of metal Y.
Advertisements
उत्तर
(a) Metal X is aluminium and metal Y is zinc.
Metal X or aluminium is resistant to corrosion and is produced by electrolysis of molten aluminium oxide. Aluminium is used in thermite welding.
Metal Y or zinc is also resistant to corrosion and is produced by reduction of zinc oxide with carbon (reducing agent). Zinc is widely used in making cathodes of ordinary dry cells.
(b) X (aluminium) is more reactive than Y (zinc). Aluminium is placed above zinc in the reactivity series.
(c) One ore of metal X (aluminium) is bauxite ore. The chemical formula of bauxite ore is Al2O3.2H2O.
(d) One ore of metal Y (zinc) is calamine ore. The chemical formula of calamine ore is ZnCO3.
(e) One alloy of metal X (aluminium) is magnalium, which consists of aluminium and magnesium. One alloy of metal Y (zinc) is brass, which consists of zinc and copper.
APPEARS IN
संबंधित प्रश्न
Why do we apply paint on iron articles?
State two conditions for the rusting of iron.
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Why is an iron grill painted frequently?
What is corrosion?
What is meant by 'rusting of iron'? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
Give the constituents and one use of brass.
Name five methods of preventing rusting of iron.
If copper is kept exposed to damp air for a considerable time, it gets a green coating on its surface. This is due to the formation of:
(a) hydrated copper sulphate
(b) copper oxide
(c) basic copper carbonate
(d) copper nitrate
Give reason.
Copper and brass utensils should be tinned.
Explain the term – rusting and give a word equation for the formation of rust. If polished iron nails are kept in three separate test tubes, state the contents in each test tube required, to prove the conditions for rusting.
Give reason for the following:
A suspension of rust is basic in nature.
Corrosion of silver causes a black layer of _______.
When one of the metals in an alloy is mercury the alloy is called _______.
Find the odd one out and give its explanation.
Write scientific reason.
Coins are made from metals and alloys.
Draw a neat labelled diagram.
Electroplating
Give preventive methods by giving examples of corrosion?
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
In ______ process a layer of molten tin is deposited on metals.
