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

Download PDF of This Page (Size: 338K)

Question 34:

  1. Under which category of mixtures will you classify alloys and why?

  2. A solution is always a liquid. Comment.

  3. Can a solution be heterogeneous?

Answer:

  1. Homogenous mixture, because they have a uniform composition throughout

  2. No, solid solutions and gaseous solutions are also possible. Examples brass and air

  3. No, solution is a homogenous mixture of two or more substances

Image of Homogeneous Mixtures

Image of Homogeneous Mixtures

Image of Homogeneous Mixtures

Question 35:

Iron filings and sulphur were mixed together and divided into two parts, ‘A’ and ‘B’. Part ‘A’ was heated strongly while Part ‘B’ was not heated. Dilute hydrochloric acid was added to both the Parts and evolution of gas was seen in both the cases. How will you identify the gases evolved?

Answer:

Part A

Part B

When dilute HCl is added to it

Sulphur remains unreacted

gas formed has a foul smell and on passing through lead acetate solution, it turns the solution black. Hydrogen gas burns with a pop sound.

Question 36:

A child wanted to separate the mixture of dyes constituting a sample of ink. He marked a line by the ink on the filter paper and placed the filter paper in a glass containing water as shown in Fig. The filter paper was removed when the water moved near the top of the filter paper.

Result for strip of filter paper

Strip of Filter Paper

Result for strip of filter paper

  1. What would you expect to see, if the ink contains three different coloured components?

  2. Name the technique used by the child.

  3. Suggest one more application of this technique.

Answer:

  1. Three different bands will be observed.

  2. Chromatography

  3. To separate the pigments present in Chlorophyll.