Question:
Describe sieving method.
Answer:
When the sizes of the components of a mixture are big enough, they can be separated with the help of sieve. A sieve is a simple mechanical device in which a mesh is attached to a frame. When the mixture is placed on the mesh and is stirred, particles of smaller size pass through the mesh while the bigger particles of the other component remain above the mesh. E.g. gram can be separated wheat, sieving of sand at construction site etc.
Is Matter Around Us Pure?
Q 1.
What is the general name of the process by which tea-leaves are separated from prepared tea ?
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.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 4.
Name any two solid substances whose mixture can be separated by sublimation.
Q 5.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 6.
What are the properties of a colloid?
Q 7.
What are aqueous solutions?
Q 8.
What is saturated solution? Explain with an example.
Q 9.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 10.
A solution contains 40 mL of ethyl alcohol mixed with 100mL of water. What is the concentration of the solution in terms of volume by volume percentage?
Q 11.
Define Brownian movement in colloids.
Q 12.
What are pure substances ? Give two examples of pure substances.
Q 13.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 14.
Name one pair of liquids which can be separated by using a separating funnel.
Q 15.
What is a solution? What are the properties of a solution?
Q 16.
How crystallization is better than evaporation?
Q 17.
Give two reasons for supposing that water is a compound and not a mixture.
Q 18.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 20.
What is meant by solute and solvent?
Q 21.
When we open the cap of a cola drink (or any carbonated beverage), why does excess of bubbles come out?
Q 22.
What are suspensions? Explain with an example.
Q 23.
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 24.
What principle is applied in centrifugation? Give examples where this method is applied to separate mixtures.
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.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 27.
State the differences between compounds and mixtures.
Q 28.
What is an unsaturated solution?
Q 29.
What is Chromatography?
Q 30.
What is an emulsion? Give examples
Q 31.
What is the general name of the materials which contain at least two pure substances and show the properties of their constituents ?
Q 32.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
Q 33.
What are the characteristics exhibited by a pure substance?
Q 34.
On the basis of composition, how matter is classified?
Q 35.
Name two properties of a substance to check its purity?
Q 36.
What are the kinds of mixture?
Q 37.
What are non-aqueous solutions?
Q 38.
Explain with an example what is a colloid?
Q 39.
What are the reasons for separating the constituents of a mixture?
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.
What are the differences and similarities between concentration and solubility?
Q 42.
Name a non-metal which is a good conductor of electricity.
Q 43.
Name the process you would use to separate a mixture of anthracene and copper sulphate ?
Q 44.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 45.
Name one pair of substances whose mixture can be separated completely by 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 the characteristics of mixture?
Q 48.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 49.
What are the constituents of brass?
Q 50.
What is a compound? Give an example.
