separation of substances

CLASS VI

                                                     SUBJECT- SCIENCE

                                                TOPIC- Separation of Substances

                                                      Revision assignment 1

Q1  Define 1) Mixtures  2) Pure substances

Q2  Can we use the method of crystallization to purify water?

Q3  Solve the following puzzle:

	1
2
									3
4
5

Across: 2 to separate husk from grains 4 method used at home to obtain butter 5 method to purify water fast

Down: 1 used to get tea by separating tea leaves 3 to get salt

      

Q5 What is the difference between homogenous and heterogenous mixtures?

Q6 Name the method

a.       In which dried stalks are beaten to separate the grains.

b.      In which mixture is allowed to fall fom a heigt and the lighter particles blow away with air and fall at a distance while heavier particles fall nearer.

c.       In which a wire mesh fixed tightly in a frame is used.

d.      In which a liquid with heavier insoluble solid impurity is left undisturbed and then removed in a separate container.

e.       In which mixture is rotated at a high speed.

Q7 In which situations ( properties of mixtures) are the following methods used?

a.       Hand picking

b.      Sublimation

c.       Filteration

d.      Loading

e.       Separating funnel

Q8 Complete the answer by filling up suitable words.

Ø  What is the difference between evaporation and crystallization?

Evaporation is the method used to separate ___ solid substances from a ____.In this liquid changes into___ form on ______.It is commonly used to obtain _____ from sea water. _____ water is collected in shallow ______ and due to the ________ water gets evaporated and ___ is left behind.                  

Crystallization is used to obtain ____ solids from a solution. It is a process in which               mixture is heated to separate a pure solid in the form of its _____ from a ____solution. It is commonly used purify ___ obtained by evaporation of sea water or to get crystals of _____ sugar.

Q9 A glass of water is kept on a table. Suddenly few dust paticles fall in it and stat floating on its  

Surface. Which methods out of the following can be used to separate the particles from water    and why?

                                           i.            Sedimentation and Decantation

                                         ii.            Loading

                                       iii.            Evaporation

                                       iv.            Filteration

Q10 Write about the method of Centrifugation.