Correct Answer:
(C)
An emulsion
An emulsion is a colloid of two or more immiscible liquids where one liquid contains a dispersion of the other liquids. Milk is an example of an emulsion. It is an example of oil in water emulsion.
Ques:
42
Which of these is not a colloid :
Correct Answer:
(D)
Honey
Among the given options, honey is not a colloid. At room temperature, honey is a super cooled liquid, in which the glucose precipitates into solid granules. This forms a semisolid solution of precipitated glucose crystals in a solution of fructose and other ingredients. Milk, blood and ice cream are colloids.
Ques:
43
Which type of colloidal system is expressed in the fog :
Correct Answer:
(A)
Liquid in a gas
When the water vapour in the air condensed to form small droplets of water, the fog is formed. When the temperature of air during winter season reaches near to dew point, the water vapour gets condensed around small particles of dust and remains suspended in the air because of their low weight.
Ques:
44
If an unsaturated sugar solution is prepared by mixing 100 grams of sugar with half litre of water, which of the following physical quantities will not change?
Correct Answer:
(D)
Volume
If an unsaturated sugar solution is prepared by mixing 100 grams of sugar with half liter of water then volume of the solution remain constant.
Ques:
45
After cutting cucumber if salt is added, then water comes out due to :
Correct Answer:
(C)
Osmosis
Osmosis is the process when water (or solvent) molecules move from a region (solution) of low concentration to a region (solution) of higher concentration through a semipermeable membrane. When salt is applied to cucumber or cut onion pieces, it makes their surrounding more concentrated than the concentration of their cell sap. Then it causes the water molecules in the cells of the cucumber and the cut onion pieces to move to the surrounding through their cell membrane (which is semipermeable).
Ques:
46
Consider the following statements :
1. During the process of osmosis, the solvent travels from the concentrated solution to the dilute solution.
2. In the reverse osmosis, external pressure is applied to the dilute solution.
Which of the statements given above is/are correct?
Correct Answer:
(D)
Neither 1 nor 2
In the process of osmosis, the solvent moves through a semi-permeable membrane into a region of higher solute concentration from lower concentration to equalize the solute concentration on two sides. While in reverse osmosis, we apply external pressure upon concentrated solution to reverse the movement of solvent, i.e. from more concentrated to weaker dilute solution. The technique is used to purify the solution by making it free from impurities.
Ques:
47
Which one of the following processes is NOT useful for purification of solid impurities?
Correct Answer:
(A)
Distillation
Distillation is the action of purifying a liquid by a process of heating and cooling. Distillation is generally used for purification of liquid impurities while sublimation and crystallization are used for purification of solid impurities.
Ques:
48
The technique of chromatography is used to –
Correct Answer:
(D)
Separate the substances from a mixture
Chromatography is a separation technique used to separate the different components in a liquid mixture. The separation is based on differential partitioning between the mobile and stationary phases. Chromatography may be preparative or analytical. The purpose of preparative chromatography is to separate the components of a mixture for more advanced use and thus it is a form of purification.
Ques:
49
Process of solid camphor into camphor vapour is called:
Correct Answer:
(D)
Sublimation
Solid camphor directly changes into camphor vapour and this process is called sublimation. The sublimation is the process in which some substances upon heating directly changes into vapour form and when cooled again directly turns into solid form.
Ques:
50
A sample of any of the following substances disappears after sometime when exposed to air like camphor, naphthalene or dry ice. This phenomenon is called :
Correct Answer:
(A)
Sublimation
Sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase. Substances like camphor, naphthalene or dry ice (solid carbon dioxide) display this phenomenon.