Questions based on case study (5+5=10)
35. Air is a homogeneous mixture and can be separated into its components by fractional distillation.
The air is compressed by increasing the pressure and is then cooled by decreasing the temperature
to get liquid air. This liquid air is allowed to warm up slowly in a fractional distillation column,
where gases get separated at different Heights depending upon their boiling point. The properties
that can be observed and specified like colour, hardness and rigidity are the physical properties.
The interconversion of states is a physical change because these changes occur without a change
in composition and no change in the chemical nature of the substance.
I) The boiling point of water is
(a) 180 degree Celsius (b) 100 degree Celsius
(c) 170 degree Celsius (d) 130 degree Celsius
II) _______________ is a process that separates a pure solid in the form of its crystals from a
solution.
(a) Simple evaporation (b) Crystallization
(c) Distillation (d) None of these
III) Which of the following is physical changes?
(a) Melting of wax (b) Rusting of iron
(c) Cooking of food (d) Burning of wax
IV) Which of the following methods would you use to separate cream from milk?
(a) Fractional distillation (b) Distillation
(c) Centrifugation (d) Filtration
V) Which of the following is a chemical change?
(a) Hammering of a nail into a piece of wood
(b) Sawing of wood
(c)rusting of an iron rod
(d) Drawing a wire of iron metal
Answers
Answer:
Air is a homogeneous mixture and can be separated into its components by fractional distillation.
The air is compressed by increasing the pressure and is then cooled by decreasing the temperature
to get liquid air. This liquid air is allowed to warm up slowly in a fractional distillation column,
where gases get separated at different Heights depending upon their boiling point. The properties
that can be observed and specified like colour, hardness and rigidity are the physical properties.
The interconversion of states is a physical change because these changes occur without a change
in composition and no change in the chemical nature of the substance.
I) The boiling point of water is
(a) 180 degree Celsius (b) 100 degree Celsius
(c) 170 degree Celsius (d) 130 degree Celsius
II) _______________ is a process that separates a pure solid in the form of its crystals from a
solution.
(a) Simple evaporation (b) Crystallization
(c) Distillation (d) None of these
III) Which of the following is physical changes?
(a) Melting of wax (b) Rusting of iron
(c) Cooking of food (d) Burning of wax
IV) Which of the following methods would you use to separate cream from milk?
(a) Fractional distillation (b) Distillation
(c) Centrifugation (d) Filtration
V) Which of the following is a chemical change?
(a) Hammering of a nail into a piece of wood
(b) Sawing of wood
(c)rusting of an iron rod
(d) Drawing a wire of iron metal
Answer:
180 degree
Cryrstallization
Rusting of iron
Centrifugation
rusting of an iron rod
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