Question:
What are suspensions? Explain with an example.
Answer:
A suspension is a heterogeneous mixture in which very fine particles (about 10-5 m size) of solid are dispersed in any medium (liquid or gas). In suspension, the solute particles are visible to the naked eye, and remain suspended throughout the bulk of the medium. The Tyndall effect is observed in this mixture. Muddy pond water, smoke coming out of a chimney, chalk-water mixture, coarse lime particles in water are examples of suspension.
Is Matter Around Us Pure?
Q 1.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 2.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 3.
What are different ways to separate solid mixtures?
Q 4.
What is the general name of the process by which tea-leaves are separated from prepared tea ?
Q 5.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 6.
(a) What is meant by (i) elements (ii) compounds, and (iii) mixtures ? Write down the names of two elements,two compounds and two mixtures.
(b) Classify the following into elements,
compounds and mixtures :
Marble,
Air,
Gold,
Brass,
Sand,
Diamond,
Graphite,
Petroleum,
Common salt,
Sea-water,
Chalk
Q 7.
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
Q 8.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 9.
What are the properties of a colloid?
Q 10.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 11.
Name the elements are in liquid state at room temperature.
Q 12.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 13.
Name the process by which the various gases of the air are separated.
Q 14.
Name any two solid substances whose mixture can be separated by sublimation.
Q 15.
What is meant by a pure substance?
Q 16.
What are the various methods to express concentration of a solution?
Q 17.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 18.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 19.
Name the process which is used in milk dairies to separate cream from milk.
Q 20.
Why do fish go in deep waters during day light?
Q 21.
What are the advantages of preparing solutions?
Q 22.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 23.
What are the kinds of mixture?
Q 24.
What are the properties of suspensions?
Q 25.
Name the following :
(a) a lustrous liquid metal.
(b) a liquid non-metal
(c) a metal which can be cut with a knife
(d) a non-metal which is good conductor of electricity.
(e) an element which melts when kept on the palm.
(f) the best conductor of heat.
Q 26.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 27.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 28.
Name a non-metal which is a good conductor of electricity.
Q 29.
What is the difference between solutions and colloids ?
Q 30.
Name one pair of liquids which can be separated by using a separating funnel.
Q 31.
On the basis of composition, how matter is classified?
Q 32.
What are different categories of pure substance?
Q 33.
Alloys cannot be separated by physical means, though it is considered mixture, Why?
Q 34.
Why air is a mixture not a compound? Give reasons.
Q 35.
Explain with an example what is a colloid?
Q 36.
What principle is applied in centrifugation? Give examples where this method is applied to separate mixtures.
Q 37.
How crystallization is better than evaporation?
Q 38.
A good method to separate alum (phitkari) from impure samples is
(a) Filtration
(b) Sedimentaion
(c) Crystallization
(d) Sublimation
Q 39.
How many elements are there which are in gaseous state at room temperature?
Q 40.
In beaker A, sugar cubes are dissolved into water while in beaker B, crushed cubes are taken. In which beaker the rate of dissolution is faster?
Q 41.
Give two reasons for supposing that water is a compound and not a mixture.
Q 42.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 43.
A 5 per cent sugar solution means that:
(a)5 g of sugar is dissolved in 95 g of water.
(b)5 g of sugar is dissolved in 100 g of water.
Choose the correct answer.
Q 44.
Which of the following will show Tyndall effect ? Why ?
(a) Salt solution
(b) Starch solution
(c)Milk
Q 45.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 46.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 47.
What are non-aqueous solutions?
Q 48.
What do you mean by strength of the solution?
Q 49.
To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293K. Find its concentration at this temperature.
Q 50.
Describe sieving method.
