NCERT Class – 9 Science solution: Chapter 2 Is Matter Around Us Pure-Part 3

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Question: 9

Two chemical species X and Y combine together to form a product P which contains both X and Y

X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct?

  1. P is a compound

  2. X and Y are compounds

  3. X and Y are elements

  4. P has a fixed composition

  5. (i), (ii) and (iii)

  6. (i), (ii) and (iv)

  7. (ii), (iii) and (iv)

  8. (i), (iii) and (iv)

Answer: D

Short Answer Questions

Question: 10

Suggest separation technique(s) one would need to employ to separate the following mixtures.

  1. Mercury and water

  2. Potassium chloride and ammonium chloride

  3. Common salt, water and sand

  4. Kerosene oil, water and salt

Answer:

  1. Separation by using separating funnel

Image of Separating Funnel

Image of Separating Funnel

  1. Sublimation

  2. Filtration followed by evaporation

Or

Centrifugation followed by evaporation/distillation

  1. Separation by using separating funnel to separate kerosene oil followed by evaporation or distillation.

Question: 11

Which of the tubes in Fig. (a) and (b) will be more effective as a condenser in the distillation apparatus?

Figure of the tubes (a) and (b)

Figure of the Tubes (A) and (B)

Answer:

  • Look for the larger surface area.

  • The presence of beads in tube (a) would provide a larger surface area for cooling.

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