NCERT Solutions For Class 9 Science Chapter 2 Is Matter Around Us Pure are prepared by CBSE student eCARE expert to score good marks in class 9. This chapter contain many topics which are very important to score good in class 9. There are some important topic/Activity mentioned below-
Topics and Sub Topics in Class 9 Science Chapter 2 Is Matter Around Us Pure:
1. What is meant by a substance?
It is a pure single form of matter. A substance has definite properties and compositions. Example – Iron
2. List the points of differences between homogeneous and heterogeneous mixtures.
|Homogeneous mixture||Heterogeneous mixture|
|Particles are uniformly distributed throughout the mixture||All the particles are completely mixed and can be distinguished with the bare eyes or under a microscope.|
|Has a uniform composition||Irregular composition|
|No apparent boundaries of division||
Noticeable boundaries of division.
1. How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25°C), which are miscible with each other?
A technique known as simple distillation can be used to separate the mixture of miscible liquids, where the difference in boiling point is more than 25°C, to name a few – kerosene and petrol. The whole concept is established on the volatility property of substances. The following are the various steps in the process of simple distillation:
(a) In a distillation flask, take the mixture.
(b) Treat the mixture with heat while a thermometer is affix.
(c) We observe evaporation of petrol as it has a low boiling point.
(d) As the vapours advance towards the condenser, a dip in the temperature causes condensation of the vapours into liquid which can be accumulated in a flask.
(e) We notice that kerosene tends to remain in the flask in a liquid state due to comparatively higher boiling point.
(f) Consequently, the liquids are separated.
2. Name the techniques used to separate the following:
(a) Butter from curd.
(b) Salt from seawater
(c) Camphor from salt
a) A process known as centrifugation is used to separate butter from curd. The process is governed on the principle of density.
b) We can use the simple evaporation technique to separate salt from seawater. Distillation causes water to evaporate leaving solid salt behind, hence the production of salt.
c) Sublimation can be used to separate camphor from salt as during the phase change, camphor does not undergo a liquid phase.