Question:
Name the process by which the various gases of the air are separated.
Answer:
fractional distillation
Is Matter Around Us Pure?
Q 1.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 2.
What are the characteristics exhibited by a pure substance?
Q 3.
What is a solution? What are the properties of a solution?
Q 4.
What are the properties of suspensions?
Q 5.
What are the differences and similarities between concentration and solubility?
Q 6.
State the differences between compounds and mixtures.
Q 7.
What are the reasons for separating the constituents of a mixture?
Q 8.
Name two properties of a substance to check its purity?
Q 9.
What factors affect the solubility of solvent and solute?
Q 10.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 11.
What are suspensions? Explain with an example.
Q 12.
What is meant by a pure substance?
Q 13.
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 14.
How crystallization is better than evaporation?
Q 15.
What are the advantages of preparing solutions?
Q 16.
Why air is a mixture not a compound? Give reasons.
Q 17.
Name the elements are in liquid state at room temperature.
Q 19.
Based on the type of solvent, how solutions are classified?
Q 20.
Based on the amount of solute in the given solution, how solutions are classified?
Q 21.
What are the properties of a colloid?
Q 22.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 23.
How many elements are there which are in gaseous state at room temperature?
Q 24.
Name the process by which the various gases of the air are separated.
Q 25.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 26.
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 27.
21.5 g of sodium chloride dissolves in 60 g of water at 25°C. Calculate the solut water at that temperature.
Q 28.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 29.
(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 30.
Fill in the following blanks :
(a)Milk is a.........solution but vinegar is a.......solution.
(b)A colloid is a........mixture and its components can be separated by the technique known as........
Q 31.
Explain what happens when a beam of light is passed through a colloidal solution.
Q 32.
9.72 g of potassium chloride dissolves in 30 g of water at 70°C. Calculate the solubility of potassium chloride at that temperature.
Q 33.
What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur ?
Q 34.
Which of the following is a sol ?
Shaving cream,
Milk,
Fog,
Soap solution,
Hairspray
Q 35.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 36.
Who used the term 'element' first time?
Q 37.
How will you distinguish a colloid from a solution ?
Q 38.
What is meant by the concentration of a solution ?
Q 39.
What is a compound? Give an example.
Q 40.
What is meant by solute and solvent?
Q 41.
What is an unsaturated solution?
Q 42.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 43.
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 44.
What are different ways to separate solid mixtures?
Q 45.
Winnowing works on what property?
Q 46.
What is the general name of the materials which contain at least two pure substances and show the properties of their constituents ?
Q 47.
State three reasons why you think air is a mixture and water is a compound.
Q 48.
Is air a mixture or a compound ? Give three reasons for your answer.
Q 49.
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
Q 50.
Name a metal :
(a) which can be easily cut with a knife
(b) which forms amalgams
©which has not fixed shape
(d) which has a low melting point
(e) which is yellow in colour
