Is Matter Around Us Pure NCERT Solution, study material, CBSE Notes

NCERT Solution: Is Matter Around Us Pure

You are given two samples of water labelled as ‘A’ and ‘B’. Sample ‘A’ boils at 100°C and sample ‘B’ boils at 102°C. Which sample of water will not freeze at 0°C? Comment.

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

What are the favourable qualities given to gold when it is alloyed with copper or silver for the purpose of making ornaments?

Pure gold is very soft as compared to gold alloyed with silver or copper. Thus for providing strength to gold, it is alloyed.

An element is sonorous and highly ductile. Under which category would you classify this element? What other characteristics do you expect the element to possess?

This element is a metal. Other characteristics expected to be possessed by the element are–lustre, malleability, heat and electrical conductivity.

Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures

(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

Fill in the blanks

(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

Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed together. Will it be a pure substance or a mixture? Give reasons for the same.

It is a pure substance because chemical composition of sugar crystals is same irrespective of its source.

Give some examples of Tyndall effect observed in your surroundings?

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.

Can we separate alcohol dissolved in water by using a separating funnel? If yes, then describe the procedure. If not, explain.

Water and alcohol are miscible.