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CBSE Class 9 · Science

Exploring Mixtures and their Separation

Official NCERT chapter from Science (Grade 9, 2026 edition) (book code iesc1). ExamMaster notes are original teaching at CBSE Class 9 depth.

This lesson follows the official chapter “Exploring Mixtures and their Separation” in Science (Grade 9, 2026 edition). The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 9
  • Medium level
  • 8 concepts

1How Can We Classify Mixtures?

Mixtures classify as homogeneous (same look throughout, a solution-story) or heterogeneous (you can still see different bits). Classify is a look-test, not a famous name. Salt water can look one; sand in water usually does not.

A pretty bottle is not the class.

Figure. A homogeneous mixture looks like one wash all the way through. A heterogeneous mixture keeps visible parts — here water sitting on sand — so you can still point at each piece.

How it works

  1. Look through the sampleSame throughout, or bits you can point to.
  2. Name homo or heteroThe class.
  3. Keep “pure substance” as a different drawer if the lesson used itMixture first.

2Solutions

A solution is a homogeneous mixture: solute sits in solvent so the look is one. Dilute versus concentrated is a how-much story, as taught. A solution is not “any wet thing” — oil on water can stay hetero.

Calling muddy water a solution because it is wet is a miss.

Figure. A solution is solute dissolved in solvent until you cannot pick the bits out by eye. Salt plus water becomes one clear mix; the salt is still there, just no longer a pile.

How it works

  1. Name solute and solventWhat sits in what.
  2. See one look throughoutSolution.
  3. Name dilute or concentrated only if amounts were comparedHow-much.

3Methods of Separation of Homogeneous Mixtures

Homogeneous mixtures separate by jobs that use a difference you cannot see as bits: evaporate the solvent, distill if boiling points differ as taught. The method must match the hidden difference. Filtering a true solution does not pull the salt back as wet crystals on the paper.

A sieve on salt water is the wrong job.

Figure. A homogeneous solution such as salt water splits by boiling point: water leaves as vapour, is cooled back to liquid, and salt stays in the first flask. That is distillation, not filtering.

How it works

  1. Name the hidden differenceEvaporate; or boil-and-cool as taught.
  2. Pick the matching methodThe separate.
  3. Refuse a filter as if it were a solution-jobHonest match.

4How Can We Separate the Components of Heterogeneous Mixtures?

Heterogeneous mixtures separate by jobs you can see: settle, decant, filter, or a magnet if a taught bit is magnetic. Sand and water can settle; a filter can catch the sand. The method matches the visible difference.

Distilling sand-water as your first move skips the easy look.

Figure. A heterogeneous sand-and-water mix splits by size: sand stays on the paper as residue; the liquid that passes is the filtrate. Filtering cannot split salt already dissolved.

How it works

  1. Name the visible bitsThe hetero look.
  2. Pick settle / decant / filter / magnet as taughtThe job.
  3. Keep the caught bit and the passed bit namedComponents.

5Tyndall Effect

Tyndall effect is a scatter-look: a beam shows up in a colloid (as taught) because bits scatter the light; a true solution does not give that path the same way. Tyndall is a test, not a flashlight toy.

Shining a torch on a wall is not this scatter-in-the-sample.

Figure. Tyndall is a light test. A true solution lets the ray through with no visible track. A colloid scatters the ray, so the path lights up. Same lamp, two mixtures.

How it works

  1. Send a beam through the sample as the lesson didThe look.
  2. See a path or notScatter or not.
  3. Hang colloid versus true solution after the lookThe effect.

6A definition is a test you can run

Mixture / solution / colloid is a test: one look throughout or not, plus a method that matches. If you only say “mixed”, you have a heading.

A smoothie advert is not the test.

Figure. The dissolve test is the definition you can run. Salt in water disappears to the eye and is a solution. Sand stays as bits, so it is still a heterogeneous mix.

How it works

  1. Look: same throughout or bitsThe object.
  2. Name the class and a matching separate-jobThe test.
  3. Then the word has contentThe definition ran.

7Name the given before the unknown

The given is the sample’s look. The unknown is the class or the method. Copy “I can still see sand” before you pick distill.

A label “mineral water” is not the given look.

Figure. Name the given parts before you choose a method. Sand, salt, and water are three different jobs: filter the sand, then distil the salt water. The method is not the first word.

How it works

  1. Write what you seeThe given.
  2. Name class or methodThe unknown.
  3. Match the job to the differenceGiven first.

8One worked case is enough at this class

One sample-and-method is enough. A page of the same salt-water clone does not add a new Tyndall.

Ten twins of “filter it” are still one hetero-job.

Figure. One worked case: boil salt water in a pan and catch the steam on a cool lid. Salt stays in the pan; liquid water collects on the lid. Same split as a distillation flask, kitchen scale.

How it works

  1. Run one classify and one separateThe case.
  2. A second only as a checkOptional.
  3. StopThis class.
Filtering salt water (a true solution) to get the salt back as wet crystals on the paper
  1. Does not work — the salt is not a caught bit
  2. Always works
  3. Is Tyndall

Match the method to the hidden versus visible difference.

Notes

  • Mapped to the official NCERT chapter “Exploring Mixtures and their Separation”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Recap

Hold these pegs from the official chapter “Exploring Mixtures and their Separation”. The wording is ExamMaster’s teaching, not a textbook recap.

How Can We Classify Mixtures?
Mixtures classify as homogeneous (same look throughout, a solution-story) or heterogeneous (you can still see different bits).
Solutions
A solution is a homogeneous mixture: solute sits in solvent so the look is one.
Methods of Separation of Homogeneous Mixtures
Homogeneous mixtures separate by jobs that use a difference you cannot see as bits: evaporate the solvent, distill if boiling points differ as taught.
How Can We Separate the Components of Heterogeneous Mixtures?
Heterogeneous mixtures separate by jobs you can see: settle, decant, filter, or a magnet if a taught bit is magnetic.
Tyndall Effect
Tyndall effect is a scatter-look: a beam shows up in a colloid (as taught) because bits scatter the light; a true solution does not give that path the same way.
A definition is a test you can run
Mixture / solution / colloid is a test: one look throughout or not, plus a method that matches.

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