Question:
When we open the cap of a cola drink (or any carbonated beverage), why does excess of bubbles come out?
Answer:
A cola (or carbonated) beverage is produced by dissolving carbon dioxide in the drink solution under pressure. Increase in pressure increases the solubility of gases. Therefore, more carbon dioxide dissolves at the higher pressure. When this pressure is suddenly released, e.g. by removing the cap of the bottle, carbon dioxide is less soluble, and it comes out in as bubbles from the solution.
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.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 3.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 4.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 5.
What is meant by solute and solvent?
Q 6.
Name one pair of liquids which can be separated by using a separating funnel.
Q 7.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 8.
What are non-aqueous solutions?
Q 9.
What is saturated solution? Explain with an example.
Q 10.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 11.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 12.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 13.
Name the apparatus you would use to separate oil from water.
Q 14.
What is a solution? What are the properties of a solution?
Q 15.
What are the various methods to express concentration of a solution?
Q 16.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 17.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 18.
What are the differences and similarities between concentration and solubility?
Q 19.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 20.
What is an unsaturated solution?
Q 21.
Define Brownian movement in colloids.
Q 22.
Name a metal which is soft and a non-metal which is hard.
Q 23.
Name a non-metal which is a good conductor of electricity.
Q 24.
What is meant by saying that metals are malleable and ductile ?
Q 25.
What are pure substances ? Give two examples of pure substances.
Q 26.
Give two reasons for supposing that water is a compound and not a mixture.
Q 27.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 28.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 29.
Name the elements are in liquid state at room temperature.
Q 30.
Why solutions do not exhibit Tyndall effect?
Q 31.
State whether the following statement is true or false : Milk is a pure substance.
Q 32.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 33.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 34.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 35.
What are the kinds of mixture?
Q 36.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 37.
Why do fish go in deep waters during day light?
Q 38.
What is Chromatography?
Q 39.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 40.
Which of the following will show Tyndall effect ? Why ?
(a) Salt solution
(b) Starch solution
(c)Milk
Q 41.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 42.
What are different categories of pure substance?
Q 43.
What are the properties of suspensions?
Q 44.
How crystallization is better than evaporation?
Q 45.
What is an emulsion? Give examples
Q 46.
(a) What is a mixture ? Give two example of mixtures.
(b) What is meant by (i) homogeneous mixtures, and (if) heterogeneous mixtures ? Give two examples of homogeneous mixtures and two of heterogenous mixtures.
(c) What is the other name of homogenous mixtures ?
Q 47.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 48.
Name two properties of a substance to check its purity?
Q 49.
What are suspensions? Explain with an example.
Q 50.
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.
