NCERT Solution: Is Matter Around Us Pure
Sample ‘B’ will not freeze at 0°C because it is not pure water. At 1 atm, the boiling point of pure water is 100°C and the freezing point of pure water is 0°C
Pure gold is very soft as compared to gold alloyed with silver or copper. Thus for providing strength to gold, it is alloyed.
This element is a metal. Other characteristics expected to be possessed by the element are–lustre, malleability, heat and electrical conductivity.
(a) A volatile and a non-volatile component.
Ans. Evaporation or distillation
(b) Two volatile components with appreciable difference in boiling points.
Ans. Distillation
(c) Two immiscible liquids.
Ans. Separation by using separating funnel
(d) One of the components changes directly from solid to gaseous state.
Ans. Sublimation
(e) Two or more coloured constituents soluble in some solvent.
Ans. Chromatography
(a) A colloid is a __________ mixture and its components can be separated by the technique known as __________.
Ans. heterogeneous, centrifugation
(b) Ice, water and water vapour look different and display different __________ properties but they are __________ the same.
Ans. physical, chemically
(c) A mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of __________ and the lower layer will be that of __________.
Ans. water, chloroform (hint– density of water is less than that of chloroform)
(d) A mixture of two or more miscible liquids, for which the difference in the boiling points is less than 25 K can be separated by the process called __________.
Ans. fractional distillation
(e) When light is passed through water containing a few drops of milk, it shows a bluish tinge. This is due to the __________ of light by milk and the phenomenon is called __________. This indicates that milk is a __________ solution.
Ans. scattering, Tyndall effect, colloidal
It is a pure substance because chemical composition of sugar crystals is same irrespective of its source.
Following are some examples of Tyndall effects.
(a) A beam of light coming through ventilation near ceiling.
(b) Beam of light coming through canopy of trees.
Water and alcohol are miscible.