Answer the following questions.
(a) Why is it possible to draw silver into a wire when even a long pencil-point breaks so easily?
(b) Why is copper used for electrical wiring in our houses?
(c) Why does a copper vessel shine again after scrubbing?
(d) Give two characteristics of alloys.
(e) What is meant by corrosion?
Answer the following questions.
(a) Why is it possible to draw silver into a wire when even a long pencil-point breaks so easily?
(b) Why is copper used for electrical wiring in our houses?
(c) Why does a copper vessel shine again after scrubbing?
(d) Give two characteristics of alloys.
(e) What is meant by corrosion?
(a) Being a metal, silver has the characteristic of ductility, that is, the ability to be drawn into wires whereas pencil, being graphite - a non−metal carbon, does not have ductility. Hence, silver can be drawn into wire but a long pencil point breaks easily.
(b) Copper is a metal and due to the presence of free electrons, it is a good conductor of electricity. Hence, copper is used to make electrical wires.
(c) The uppermost layer of copper vessels gets corroded due to regular contact with air and moisture. While scrubbing them, the corroded layer of the vessels is removed due to friction, and the copper vessels shine again.
(d) Two characteristics of alloys are as follows:
(i) The constituents of an alloy are present in specific proportion.
(ii) Physical properties of an alloy differ from the constituents while chemical properties remain the same.
(e) Corrosion refers to the process of gradual destruction of material, usually metal, by chemical reaction with the environment. For example, if iron articles are placed in an open environment, they get covered with a reddish substance. This is due to the reaction of iron with the gases and moisture present in the environment.
(a) Being a metal, silver has the characteristic of ductility, that is, the ability to be drawn into wires whereas pencil, being graphite - a non−metal carbon, does not have ductility. Hence, silver can be drawn into wire but a long pencil point breaks easily.
(b) Copper is a metal and due to the presence of free electrons, it is a good conductor of electricity. Hence, copper is used to make electrical wires.
(c) The uppermost layer of copper vessels gets corroded due to regular contact with air and moisture. While scrubbing them, the corroded layer of the vessels is removed due to friction, and the copper vessels shine again.
(d) Two characteristics of alloys are as follows:
(i) The constituents of an alloy are present in specific proportion.
(ii) Physical properties of an alloy differ from the constituents while chemical properties remain the same.
(e) Corrosion refers to the process of gradual destruction of material, usually metal, by chemical reaction with the environment. For example, if iron articles are placed in an open environment, they get covered with a reddish substance. This is due to the reaction of iron with the gases and moisture present in the environment.
