NCERT Solutions for Class 9 Science Chapter 2: Is Matter Around Us Pure

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The NCERT Solutions for Class 9 Science are provided in this article. Some of the important concepts in Class 9 Science Chapter 2 Is Matter Around Us Pure are:

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NCERT Solutions for Class 9 Science Chapter 2


Important Topics in Class 9 Science Chapter 2 Is Matter Around Us Pure?

Matter is any substance that occupies space and has a mass and volume. It exists primarily in three forms: solid, liquid and gas. Any substance, either an element or a compound, that consists of only one type of atom or molecule is defined as pure. For instance, the salt which we use in our kitchen is made up of only one kind of molecule, which is, the Iodine molecule.

Three States of Matter

The three primary states of matter found in our surroundings are solid, liquid and gas. There are several other states of matter found only in specific conditions, like Bose-Einstein condensate and neutron degenerate matter.

Example: How can the states of matter be determined?

Solutions: The components which helps to determine the states of matter are:

  • The kinetic energy level is a vital component as it impacts the motion of the particles.
  • The force of attraction between different atoms also helps to determine the state of matter.
  • The space between every particle.

Colloids

Colloids, otherwise known as colloidal solutions, are a type of mixture where the micro-insoluble particles of one substance are found suspended in another. Colloid, in simple words, refers to a solution which is the size of solute particles ranging between 1nm - 1000 nm.

Example: Determine what happens when a beam of light is passed through a colloidal solution.

Solutions: When a beam of light is passed through a colloidal solution, its path becomes visible. It happens due to the fact that colloidal particles usually have a large enough size to scatter the beam of light passed. This process is otherwise called the tyndall effect.

Suspension

Suspension can be defined as a heterogeneous mixture that comprises many different particles mixed in a solution ranging around a 1000 nanometers. It can be practically seen when solid particles are scattered within a liquid without dissolving in it.

Example: List some of the important properties of Suspension.

Solution: Some of the important properties of Suspension include:

  • Suspension can be defined as a heterogeneous mixture of solid particles found in a liquid.
  • Usually in suspension, the particles are visible with the naked eyes.
  • Normally, the diametric range of the particles are roughly around 1000 nm ( i.e.,100 times that of a solution).

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CBSE X Related Questions

  • 1.
    Due to change in length and area of cross-section of a conductor, resistance of conductor changes while resistivity does not change. Why ?


      • 2.
        Rays from the sun converge at a point 25 cm behind a convex lens. The distance at which an object be placed in front of the lens to get a virtual image, is:

          • 20 cm
          • 40 cm
          • 50 cm
          • More than 50 cm

        • 3.
          State two differences between the act of chewing food and salivation on sight of food.


            • 4.
              How many bulbs of resistance \( 8 \ \Omega \) each should be connected in parallel combination to draw a current of \( 2 \text{ A} \) from a battery of \( 4 \text{ V} \) ?


                • 5.
                  When you look at an object very close to your eyes, the:

                    • Ciliary muscles of your eye contract and the eye lens becomes thick.
                    • Ciliary muscles of your eye get relaxed and the eye lens becomes thick.
                    • Ciliary muscles of your eye contract and the eye lens becomes thin.
                    • Ciliary muscles of your eye get relaxed and the eye lens becomes thin.

                  • 6.
                    From the given situations, identify 'Chemotropic' and 'Geotropic' movements in parts of plants, respectively:
                    (i) Growth of pollen tube towards ovule.
                    (ii) Movement of sunflower towards sunlight.
                    (iii) Movement of root towards Earth/Gravity.
                    (iv) Movement of leaves due to breeze.

                      • (i) and (iii) respectively
                      • (iii) and (i) respectively
                      • (i), (ii) and (iii), (iv) respectively
                      • (i), (iii) and (ii), (iv) respectively

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