Ans: A mixture is a substance formed by mixing two or more than two substances in any proportion by weight in which components of a mixture retain their identity and properties.
2. What do you understand by saturated solution?
Ans: The solution which cannot dissolve any more solute at a particular temperature is called saturated solution.
3. What do you understand by unsaturated solution?
Ans: The solution which can dissolve more solute at a particular temperature is called unsaturated solution.
4. What is a supersaturated solution?
Ans: The solution in which more solute is dissolved by increasing the temperature of a saturated solution is called supersaturated solution.
5. What do you mean by solute?
Ans: The substance which gets dissolved into other substance to form solution is called solute.
6. What is solution?
Ans: Solution is a homogeneous mixture of solute and solvent.
7. What do you mean by solvent?
Ans: The substance which dissolves solute to form solution is called solvent.
8. What is solubility?
Ans: The solubility of a substance at a given temperature is defined as the quantity of the substance that can be dissolved in 100 parts of the solvent at that temperature to give a saturated solution.
9. What is solubility curve?
Ans: A curve obtained by plotting the solubility of a substance at different temperatures is known as solubility curve.
10. What is a crystal?
Ans: Crystal is a homogeneous solid particle which has definite geometrical shape and bounded by plane surfaces meeting at sharp edges.
11. How is supersaturated solution prepared?
Ans: Supersaturated solution is prepared by dissolving more solute in saturated solution by increasing its temperature.
12. The solubility of sodium nitrate is 88 gm at 20°c. What does it mean?
Ans: It means that at 20oC, 88 gm of sodium nitrate dissolves in 100 gm of water to form the saturated solution.
13. Why is it necessary to mention the temperature along with solubility?
Ans: It is necessary to mention temperature along with solubility because solubility of a solute changes with the change in temperature.
14. What are crystalline substances?
Ans: The substances which have definite geometrical shape are called crystalline substances.
15. What are amorphous substances?
Ans: The substances which do not have definite geometrical shape are called amorphous substances.
16. What is meant by dilute solution?
Ans: The solution in which comparatively less amount of solute is dissolved in the fixed amount of solvent is called dilute solution.
17. What is meant by concentrated solution?
Ans: The solution in which comparatively more amount of solute is dissolved in the fixed amount of solvent is called concentrated solution.
18. What is homogeneous mixture?
Ans: The mixture in which the particles of the components are mixed uniformly is called homogeneous mixture.
19. What is heterogeneous mixture?
Ans: The mixture in which the particles of the components are not mixed uniformly is called heterogeneous mixture.
20. What is crystallization?
Ans: The process of making crystals is called crystallization.
21. Define suspension.
Ans: A suspension is a heterogeneous mixture in which small particles of the solids are spread throughout a liquid without dissolving in it.
22. Define colloid.
Ans: When the diameter of the dissolved particles in the mixture ranges between the sizes of suspension and solution, such a mixture is known as colloid.
23. What is decantation?
Ans: The process of separation of clear liquid from the sediment is known as decantation.
24. What is filtration?
Ans: Filtration is a process by which insoluble solid particles from a solution are separated by a filter paper.
25. What is centrifuging?
Ans: The method of separation of solid from a solution with the help of a centrifuge is called centrifuging.
26. What is distillation?
Ans: The process of purifying a liquid by successive evaporation and condensation is called distillation.
27. What types of substances are separated by sublimation?
Ans: The substances which changes directly into gaseous state due to heat and converts into solid due to cooling can be separated by using sublimation method.
28. What is evaporation?
Ans: The process of conversion of liquid into vapour on heating is called evaporation.
29. What is a mixture ?
Ans: A mixture is mass formed by mixing two or more substances in any proportion by weight without any change in the individual property of the components.
30. Define homogeneous mixture and heterogeneous mixture with examples.
Ans:
1. Homogeneous mixture: The mixture in which components of the mixture are mixed uniformly with each other is called homogeneous mixture. For example: salt solution, sugar solution etc.
2. Heterogeneous mixture: The mixture in which components of the mixture are not mixed uniformly with each other is called a heterogeneous mixture. For example: muddy water, milk, smoke etc.
31. Differentiate between homogeneous mixture and heterogeneous mixture.
Ans:
| Homogeneous mixture | Heterogeneous mixture |
| The components are distributed uniformly. | The components are not distributed uniformly. |
| Each component of the mixture can not be identified by naked eyes. | The components of the mixture can be identified by naked eyes. |
| A solution is a homogeneous mixture. | A suspension is a heterogeneous mixture. |
32. What do you mean by solution? Give one example.
Ans: Solution is defined as a homogeneous mixture of two or more substances. For example sugar solution, salt solution etc.
33. Define the terms 'solute' and 'solvent' with one example.
Ans: The substance which gets dissolved and is present in smaller proportion is called the solute. In sugar solution, sugar is solute.
The substance which dissolves the solute and is present in larger proportion is called the solvent. In salt solution, water is solvent.
34. Define: Unsaturated solution
Ans: Unsaturated solution: A solution which can dissolve more solute at a particular temperature is known as unsaturated solution at that temperature.
35. Define: Saturated solution
Ans: Saturated solution: A solution which cannot dissolve any more solute at a particular temperature is known as saturated solution at that temperature.
36. Define: Supersaturated solution
Ans: Supersaturated solution: When more quantity of solute is dissolved by raising the temperature of a saturated solution, it is called a supersaturated solution.
37. Define: Amorphous solids
Ans: Amorphous solids: Those solid substances that do not have any definite geometrical forms or shapes are called amorphous solids.
38. Define: Crystalline solids
Ans: Crystalline solids: Those solid substances that have fixed geometrical shapes along with definite and rigid morphology are called crystalline solids.
39. Define: Dilute solution
Ans: Dilute solution: A solution in which the amount of solution is small compared to that of the solvent is known as a dilute solution.
40. Define: Concentrated solutio
Ans: Concentrated solution: A solution in which the amount of the solute is large compared to that of the solvent is known as concentrated solution.
41. Differentiate between Saturated solution and unsaturated solution.
Ans: The differences between saturated solution and unsaturated solution are as follows:
| Saturated solution | Unsaturated solution |
| A solution in which more solute can not dissolve at a particular temperature. | A solution in which more solute can dissolve at a particular temperature. |
| It may be unsaturated on heating. | It remains unsaturated on heating. |
| Precipitation of the solute appears on cooling. | Precipitation of the solute does not appears on cooling. |
| It has more density. | It has less density. |
| It has more concentration of the solute. | It has less concentration of the solute. |
42. Differentiate between amorphous and crystalline solids.
Ans:
| Amorphous solid | Crystalline solid |
| These substances do not have definite geometrical shape. | These substances have definite geometrical shape. |
| Glass, rubber plastics are the examples of amorphous solid. | NaCl, CuSO4 are the examples of crystalline solid. |
43. Differentiate between dilute and concentrated solution.
Ans:
| Concentrated Solution | Dilute solution |
| If the amount of solute is comparatively higher in a solution then it is a concentrated solution. | If the amount of solute is comparatively lower in a solution then it is a dilute solution. |
| It is more reactive. | It is less reactive. |
44. “Solution is a homogeneous mixture”. Justify.
Ans: A mixture which can not be seen through our naked eyes is called homogeneous mixture. Since solution is the mixture of two or more substances in which components of solvent is in larger proportion than in solute, it is called homogeneous mixture of solution. Example: Salt and water etc.
45. How can you identify unsaturated, saturated and supersaturated solutions ?
Ans: Take three beakers; put a small crystal of solute.
If the concentration is same and solid do not dissolve the solution is saturated mixture of solution.
If the solid crystal dissolves partially or completely then the solution is unsaturated.
If the solid crystal grows in size and the concentration of solution falls then it is called supersaturated.
46. List some significances of a solution in our daily life.
Ans: Significances of a solution in our daily life are listed below:
1. Plants take mineral salts in the form of solution from the soil.
2. The food that we take absorbed in the form of solution.
3. Aquatic animals take oxygen dissolved in water.
4. We take medicines in the form of solution.
47. When a saturated solution at a high temperature is cooled, why is the solution separated as a solid ?
Ans: When a saturated solution at a high temperature is cooled, inter molecular space between the molecules of the solution decreases. As a result, no more solute can remain in a solution separating out as a solid crystal.
48. If some solute added can be dissolved in a solution at a certain temperature, what is the type of solution ?
Ans: It is unsaturated solution.
49. If the crystals of Copper Sulphate are kept in its saturated and super saturated solution separated, what will happen to the crystals ?
Ans: The size of CuSO4 crystal remains same on saturated solution and the size of the CuSO4crystal increases in supersaturated solution.
50. If the concentration of a solution reduces and crystal appears when solute is added to the solution at temperature 40°C, name the type of solution.
Ans: It is saturated solution.
51. What is meant by the solubility of a substance? Write down the formula which is used to calculate the solubility.
Ans: The solubility of a substance at a particular is defined as the amount of solute dissolved in 100gm of solvent to a saturated solution at that temperature. Mathematically,
Solubility =
52. The solubility of sugar at 30°C is 220. What does it mean ?
Ans: This means 220g of sugar is dissolved in 100g of solvent to make saturated solution at 30° C
53. Differentiate between colloids and suspension.
Ans: The components of colloidal can be separated by sedimentation or filtration.
| Colloid | Suspension |
| The diameter of the particle of a substance in a solvent is 10-3cm to 10-7cm and particles are not visible to naked eyes. | The diameter of the particle is greater than 10-3cm in diameter and particles are visible to naked eyes. |
| The components of colloidal cannot be separated by sedimentation or filtration. | The components of colloidal can be separated by sedimentation or filtration. |
54. What is a solubility curve ? What can be known from the solubility curve ?
Ans: A curve obtained by plotting the solubility of a substance at different temperature is known as solubility curve. Solubility of a substance at different temperature can be known from the solubility curve.
55. List any four applications of a solubility curve.
Ans: Applications of a solubility curve are listed below:
1. The solubility of a substance at a particular temperature can be found.
2. The solubilities of two or more substances at the same temperature can be compared.
3. The solubility curve shows how the solubility of substance varies with the rise in temperature.
4. With the help of solubility curve, the amount of solute that precipitates out when a saturated solution at higher temperature is cooled to a lower temperature can be calculated.
56. What is crystal ? How are crystals prepared ?
Ans: Crystals are homogeneous solids bounded by plane surfaces, meeting in sharp edges and having regular and definite geometrical shape. When a saturated solution of a solid in a liquid at higher temperature is allowed to cool then crystals are formed.
57. What is crystallization ?
Ans: When a saturated solution of a solid in a liquid at higher temperature is allowed to cool, a quantity of solid is deposited in the form of crystals. This process is known as crystallization.
58. Explain the process of formation of copper sulphate crystals.
Ans: Take a solution of copper sulphate in basin and make it saturated by dissolving more copper sulphate or by heating the solvent .Supply the heat until small crystals appears and then remove the heat and cool it in air. Separate the crystal from the mother liquor and put it on a filter paper to dry. Hence in this way crystal of CuSO4is prepared.
59. Temperature is mentioned along with the solubility of a substance. Why ?
Ans: Temperature is mentioned along with the solubility of a substance because solubility changes on changing the temperature.
60. The solubility of CaSO4 at 20°C is 21. What does it mean ?
Ans: It means 21 gm CuSO4 can dissolve in 100gm of water to make saturated solution of CuSO4 at 20°C.
61. List the types of mixture on the basis of size of particle.
Ans: Mixtures are of three types on the basis of size of particles, they are:
1. Solution (<10-7cm)
2. Colloids (10-7cm to 10-3cm)
3. Suspension (>10-3cm)
62. Define: Solution
Ans: Solution: Homogeneous mixture of two or more substance is called solution. In solution, the particles are of 10-7cm or smaller in size. Example: sugar solution, salt solution
63. Define: Colloids
Ans: Colloids: If the particles in a homogeneous mixture are 10-7 to 10-5 cm in size, such mixture is known as colloids. This state falls in between solution and colloids.
64. Define: Suspension
Ans:
65. Why does a solute dissolve quickly at high temperature and at powdered state ?
Ans: When solid is heated, its molecule gain more energy and start to vibrate vigorously. On heating solvent, the molecules of liquid gain more energy and start moving vigorously, so that, intermolecular space increases. When the intermolecular space increases, then the dissolving capacity also increases. Thus, the solubility of a substance increases on heating.
If the solute particular are converted into powder, then the surface area of solute increases. It makes the molecule of solvent come in contact with molecules of solute at faster rate and it dissolves quickly.
66. Define the terms 'solute' and 'solvent' with one example each.
Ans: Solute is defined as the substance which gets dissolved and is present in smaller proportion is called the solute. Example: In sugar solution, sugar is solute.
Solvent is defined as the substance which dissolves the solute and is present in larger proportion is called solvent.
Example: In salt solution, water is a solvent.
67. What is the saturated solution ?
Ans: The solution in which more amount of solute can dissolve in given solvent at given temperature.
68. What is meant by the solubility of a substance ? Write down the formula which is used to calculate the solubility.
Ans: The solubility of a substance at a particular is defined as the amount of solute dissolved in 100gm of solvent to a saturated solution at that temperature.
Mathematically,
Solubility =
69. List any three applications of a solubility curve.
Ans: Applications of a solubility curve are listed below:
1. The solubility of a substance at a particular temperature can be found.
2. The solubility's of two or more substances of the same temperature can be compared.
3. The solubility curve shows how the solubility of substance varies with the rise in temperature.
4. With the help of solubility curve, the amount of solute that precipitates out when a saturated solution at higher temperature is cooled to a lower temperature can be calculated.
70. What is crystal ? How are crystals prepared ?
Ans: Crystals are homogeneous solids bounded by plane surfaces, meeting in sharp edges and having regular and definite geometrical shape. When a saturated solution of a solid in a liquid at higher temperature is allowed to cool then crystals are formed.
71. What is crystallization ?
Ans: When a saturated solution of a solid in a liquid at higher temperature is allowed to cool, a quantity of solid is deposited in the form of crystals. This process is known as crystallization.
72. Temperature is mentioned along with the solubility of a substance. Why ?
Ans: Temperature is mentioned along with the solubility of a substance because solubility changes on changing the temperature.
73. The solubility of CaSO4 at 20°C is 21. What does it mean ?
Ans: It means 21 gm CuSO4 can dissolve in 100gm of water to make saturated solution of CuSO4 at 20°C.
74. Give Reasons: In winter, soap does not properly dissolve in water.
Ans: It is because in winter, due to low temperature of water, it cannot dissolve enough soap in it to form proper lather.
75. Give Reasons: A saturated solution becomes unsaturated on heating.
Ans: When a saturated solution is heated, the intermolecular space increases and more particles of solute can be adjusted there.
76. Give Reasons:
Water is the universal solvent.
Ans: Water can dissolve many types of solute in it so, it is called universal solvent.77. Give Reasons: Brass is a solution.
Ans: Brass is an alloy formed by mixing two metals: copper and zinc in a proper ratio. It is special type of solution of two solutes and the particles of any solute of the component is not visible in it.
78. Give Reasons:
Temperature is mentioned with solubility.
Ans: Since the solubility of substance is different at different temperatures, the temperature is mentioned with solubility.
79. When 15gm of a saturated solution of sodium nitrate at 30°C is cooled down at 10°C, then how much sodium nitrate will be precipitated if solubility of sodium nitrate at 30°C is 95 and 10°C is 30 respectively ?
Solution:
According to the statement :
At 30°C , 95g of NaNO3 form 195 g of saturated solution
At 10°C, 30g of NaNO3, form 130 g of saturated solution
The difference in the weight of solution is : 195 - 130 = 65g
It shows that,
195 g of saturated solution is cooled from 30°C to 10°C
it separates
Therefore, 15 g of saturated solution is when cooled from 30°C to 10°C
It separates
Thus, 5g sodium nitrate is separated by cooling the solution.
80. If 70 gram of a saturated solution of sodium nitrate in water at 30°C, contains 15 gram of solute, find the solubility of sodium nitrate at that temperature.
Solution:
Weight of saturated solution(W) = 70gm
Weight of solute(W1) = 15gm
Weight of solvent (W2) = Weight of saturated solution - Wt. of solute
= (70 - 15)g
= 55g
Solubility(s) = ?
We know that,
Solubility(s) =
=
= 27.27
Therefore, the solubility of sodium nitrate at 30°C is 27.27.
81. At 20°C, 4.1 gram of sugar dissolves in 2.5 gram of water to form a saturated sugar solution. Find the solubility of sugar.
Ans: Solution:
Weight of solute (W1) = 4.1gm.
Weight of solvent (W2) = 2.5 gm.
Solubility at 20°C(s) = ?
We know that,
Solubility (S) =
= 164
Therefore, the solubility of sugar at 20°C is 164 .
82. At 40°C, 45gm of KCl dissolves in 30gm of water to form a saturated solution. Find the solubility of KCl.
Solution:
Weight of solute (W1) = 45g
Weight of solvent (W2) = 30g
Solubility at 40° C =?
We have,
Solubility at 40°C =
=
= 150
Therefore, the solubility of potassium chloride at 40° C is 150.
83. At 30°C, 103 gm of saturated solution of NaCl contains 30.9gm of NaCl. Find the solubility of NaCl at 30°C.
Solution:
Weight of solute (W1) = 30.9g
Weight of saturated solution (W) = 103g
Weight of solvent (W2) = Weight of saturated solution (W) – Weight of solute (W1)
= (103 – 30.9)g
= 72.1 g
We know that,
Solubility at 30° =
=
= 42.86
Therefore, the solubility of NaCl at 30°C is 42.86.
84. 5g of water dissolves 60 gm of NH4NO3 in it to form a saturated solution at 30°C. Calculate the solubility of NH4NO3 at that temperature.
Solution:
Weight of solute (w1) = 60g
Weight of solvent (w2) = 5g
We have,
Solubility at 30° =
=
= 1200
Therefore, the solubility of NH4NO3 at 30°C is 1200.
85. How much of CuSO4 crystals will be separated if 25 g of saturated solution of CuSO4 at 60°C is cooled down to 30°C if solubility of copper sulphate at 60°C and 30°C are 50 and 30 respectively.
Solution:
At 60° C, 50g of copper solution form 150g of saturated solution.
Similarly at 30° C, 30g of copper solution form 130g of saturated solution.
The difference in the weight of solution = (150 – 130)g
= 20g
From above,
When 150g of saturated solution is cooled from 60° C to 30° C it separates out 20g of CuSO4.
When 1g of saturated solution is cooled from 60° C to 30° C it separates out 20/150 g of CuSO4.
When 25g of saturated solution is cooled from 60° C to 30° C it separates out
Therefore, 3.33g of CuSO4 is separated on cooling 25g of CuSO4 from 60°C to 30°C.
86. What is a solubility curve ? What can be known from the solubility curve ?
Ans: A curve obtained by plotting the solubility of a substance at different temperature is known as solubility curve. Solubility of a substance at different temperature can be known from the solubility curve. A diagram of solubility curve is shown in the figure below:
.