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Q1. Is air around us a compound or a mixture?
Q2. Water is a compound. Justify.
Q3. Differentiate between homogeneous and heterogeneous mixtures.
Q4. Give reasons for the following:
(a) Copper is used for making electric wires.
(b) Graphite is used for making electrode in a dry cell.
Answers
Answer:
Air is a mixture of several gases such as oxygen,nitrogen,carbon dioxide, argon, water vapour,etc.
Water is a compound because compounds are made up of different elements in fixed proportion by mass likecouse, in water molecule, hydrogen and oxygen form compound H2O in the ratio of 1. 8 by mass.
A homogenous mixture is that mixture in which the components mix with each other and its composition is uniform throughout the solution. A heterogenous mixture is that mixture in which the composition is not uniform throughout and different components are observed.
Copper electrical wires are safer to use than wires made of most other conductive metals because they are resistant to heat. As you can see, copper is the preferred metal for electrical wires for several reasons. It has high electrical conductive; it's inexpensive; it's ductile; and it's thermal resistant.
Graphite is used in making electrodes because it is a good conductor of electricity due to the presence of free electrons. One valence electron of each carbon atom remains free and thus it is a good conductor of electricity.
Answer:
1)mixture
2)yes, water is compound of H20
3)homogeneous mixture is composition of a mixture which is uniform throughout
heterogeneous mixture is composition of a mixture which is not uniform throughout
4) copper is used for making electric wires because of the the lower level of resistivity and the conductivity of electricity
graphite is used for making electrode in a dry cell because due to the presence of free cells.