NCERT Class – 9 Science solution: Chapter 2 Is Matter Around Us Pure-Part 8

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Question 31:

Classify the substances given in Fig into elements and compounds

Image of elements and compounds

Elements and Compounds

Image of elements and compounds

Answer:

Elements and Compounds
Elements and Compounds

Elements

Compounds

Wood

Diamond (carbon)

Sand

Question 32:

Which of the following are not compounds?

  1. Chlorine gas

  2. Potassium chloride

  3. Iron

  4. Iron sulphide

  5. Aluminium

  6. Iodine

  7. Carbon

  8. Carbon monoxide

  9. Sulphur powder

Answer:

  1. Chlorine gas

  2. Iron

  3. Aluminium

  4. Iodine

  5. Carbon

  6. Sulphur powder

Image of What is a compound

Image of What is a Compound

Image of What is a compound

Long Answer Questions

Question 33:

Fractional distillation is suitable for separation of miscible liquids with a boiling point difference of about or less. What part of fractional distillation apparatus makes it efficient and possess an advantage over a simple distillation process. Explain using a diagram.

Answer:

The fractionating column packed with glass beads provides a surface for the vapours to collide and lose energy so that they can be quickly condensed and distilled. Also length of the column would increase the efficiency.

Image of Fractional distillation

Fractional Distillation

Image of Fractional distillation