تجرباتی تکنیکیں

Written by Dr. Ayesha Nadeem (Chemistry)

گیارہویں جماعت · کیمیا · 8 سوالات

نام: ____________________ تاریخ: ____________

Components of a mixture of liquids with different boiling points are separated by:
- A Sublimation
- B Filtration
- C Fractional distillation
- D Crystallisation
In paper chromatography, substances separate because of differences in:
- A Their attraction to the paper and the solvent
- B Density
- C Colour only
- D Mass only
Pure solid compounds are purified from solutions by:
- A Distillation
- B Centrifuge only
- C Crystallisation
- D Evaporation to dryness only
The Rf value in chromatography is the ratio of:
- A Solvent to substance
- B Distance moved by substance to distance moved by solvent
- C Temperature to time
- D Mass of substance to solvent
Solvent extraction works because a solute is:
- A A gas
- B Always ionic
- C A catalyst
- D More soluble in one solvent than another
Which technique separates a mixture of two liquids that do not mix?
- A Sublimation
- B Crystallisation
- C Separating funnel
- D Filtration
Sublimation is used to separate:
- A Sugar from water
- B Oil from water
- C Iodine from sand
- D Salt from water
Filtration separates:
- A Two liquids
- B Two gases
- C An insoluble solid from a liquid
- D Dissolved salts

جوابی کلید

1. C, 2. A, 3. C, 4. B, 5. D, 6. C, 7. C, 8. C

Fractional distillation separates liquids by boiling point.
Components travel at different speeds depending on their affinity to the two phases.
Crystallisation gives pure crystals from a saturated solution.
Rf = distance of spot / distance of solvent front.
The solute moves into the solvent in which it dissolves better.
The denser liquid is drained off.
Iodine changes directly to a gas on heating.
The filter paper traps the solid.