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Subject:

science-chemistry

Class:

class VII

Key Concepts

substances, elements, solution, mixtures, states of matter, solid, liquid, gases

essential questions

1. How do pure substances and mixtures compare?
2.How can matter be classified?
3. How is matter classified?
4. How can mixtures be separated?

Remembering:

  1. What is the principle of chromatography based on?
  2. Name the technique used to separate a solid from its solution.
  3. Name two methods by which solid and solid mixture can be separated from non magnetic impurities.
  4. Name the substance you will add to speed up sedimentation
  5. Fill in the blanks:

a)____ are made up of same kind of atoms.

b) ____ and ____ are pure substances

c) In a ___substances are not combined chemically

d) Clay is separated from water by the method called _____

e) ___ is a process to obtain a very pure form of solid dissolved in a liquid

f) Camphor and ammonium chloride can_____

6. Give one word:

a) The solid particles which remain on the filter paper after filtration

b) The liquid which evaporates and then condenses during the process of distillation

c) The process of transferring the clean liquid after the solid settles at the bottom of the container_____

d) The process by which two miscible liquids are separated.

e) Mixtures can be _____ or _____

f) Use of a ____ to separate the components of a mix of solids based on the difference in the size of the components

g) ___ is used when the constituents of a mixture of solids have a difference in their weights

7. Match the following:

Column A                                                                    Column B

a)To separate grain from chaff                                 a) Filtration

b) To separate sawdust from water                         b) Sedimentation

c) To separate iodine from sodium chloride         c) winnowing

d) To separate iron fillings from sand                    d) sublimation

e) It is used to separate sand and water                 e) handpicking

     MCQ

  1. Name of the element in Hemoglobin: a) Iron  b) Copper  c) Nickel  d) Sodium
  2. Name the metal in Chalk: a) calcium  b) Nickel  c) Magnesium  d) Sodium
  3. Name the metal present in chlorophyll: a) Sodium  b) Magnesium  c) Nickel  d) Iron
  4. Select the elements and compounds from the following list:  iron, plaster of paris, chalk, common salt, aluminium, calcium oxide, cane sugar, carbon, silica, sodium sulphate, calcium, potassium, uranium, carbonate, silver, carbon dioxide
  5. Name the process by which the components of following mixtures can be separated: a) Iron and Sulphur   b) Ammonium chloride and sand   c) Common salt from sea water  d) Chaff and grain  e) water and mustard oil  f) sugar and waste
  6. On which principle is are the following based on: a) Sublimation   b) filtration  c) sedimentation  d) decantation  e) solvent  f) extraction method  g) magnetic separation  h) fractional distillation
  7. In chromatography the filter paper is: a) stationery paper  b) mobile phase  c) mixture  d) none of the above
  8. Winnowing is method used to separate  a) Chaff from grains  b) stones from rice  c) oil from water  d) salt from sand
  9. During filtration the substance left behind on the filter paper is called_____ a) distillate   b) filtrate  c) sublimate   d) residue
  10. Loading is the process in which a) impurities become heavy and sink to the bottom  b) impurities float on the top  c) impurities vaporize  d) none of the these

understanding:

  1. What are the characteristics of a pure substance? Why do we need them?
  2. How is distillation more advantageous than evaporation?
  3. What is chromatography? Why is it so called?
  4. Is the food that we eat a mixture?
  5. Fill in the blanks:

a) Iodine, camphor, napthalene, ammonium chloride and dry ice are same substances that_____

b) Filtration is used to separate fine particles of ____ sold from a liquid

c) Loading is basically speeding up____

d) A ___ substance has only one kind of matter

e) The composition and properties of a ____ mix is uniform throughout.

f) An____ is a homogeneous mix of two or more metals

g) Chalk powder dissolved in water is an example of a chalk powder dissolve in water is an example of  a____           h) A___ is formed when one liquid is dispersed throughout another liquid.

i) Immiscible liquids are separated by using a _____

6. Write true or false:

a) Milk is an emulsion

b) A heterogeneous mix has a uniform composition throughout the mixture

c) The constituents of a mixture can only be separated by chemical means

d) Hand picking can be used as a separation techniques if the particles size of the constituents of the mix is the same.

    MCQ

  1. The components of crude petroleum can be separated by:  a) distillation  b) evaporation  c) filtration  d) fractional distillation
  2. The constituents of a mixture are present in a)  a fixed ratio  b) variable ratio  c) the ratio is 2:1   d) none
  3. The methods of separating components of a given mix are based on the : a) Physical properties and state of the components  b) color of the components only  c) State of components  d) none
  4. Fractional distillation is used to separate liquids having an appreciable difference in their : a) shape and size  b) solubility  c) boiling points  d) none

Application:

  1. How will you separate a mixture of common salt, chalk powder and powdered camphor? Explain
  2. How can you separate iron metal from non metal impurities.

     MCQ

  1. A pure liquid is obtained from a solution by: a) Evaporation  b) distillation  c) alteration  d) crystallization
  2. Select the correct alternative from the choice given for a homogeneous mixture: a) distilled water  b) sand and water  c) tap water  d) water and oil
  3. Select the correct alternative from the choice given for a set of mixture: a) ink, honey, ice cream,, milk   b) milk, brass, silver, honey   d) butter, petroleum, tap water, iron
  4. The different constituents of ink are separated by: a) Handpicking  b) paper chromatography  c) filtration  d) magnetic separation

Analysis:

Evaluation:

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