Sorting and Separation of Materials Quiz

Which of the following cannot be separated using magnetic separation?

1. Iron filings from sand
2. Aluminium chips from iron scraps
3. Iron nails from sawdust
4. Steel pins from paper

Answer: (b) Aluminium chips from iron scraps

A student is given a mixture of kerosene, water, and sand. Which of the following is the most effective and correct order to separate all three components?

1. Use a separating funnel to remove kerosene, then decant water, and finally filter out sand
2. Filter the mixture to remove sand, use a separating funnel for water and kerosene, then evaporate water
3. Allow sedimentation, decant kerosene, filter water, then use evaporation
4. Filter to remove sand, allow the liquids to settle, then use a separating funnel for kerosene and water

Answer: (d) Filter to remove sand, allow the liquids to settle, then use a separating funnel for kerosene and water

Which of the following statements about thermal conductivity is true?

1. Metals are poor conductors of heat compared to non-metals.
2. Insulators have high thermal conductivity.
3. The thermal conductivity of a material is independent of its temperature.
4. Metals generally have high thermal conductivity due to the mobility of their electrons.

Answer: (d) Metals generally have high thermal conductivity due to the mobility of their electrons.

During a materials lab, a student observes the following about one sample: 1. It does not bend under pressure. 2. It cannot be scratched by a metal rod. 3. It does not break when dropped, but it also does not flex at all. Based on these combined observations, which property is most dominant in this material?

1. Hardness
2. Flexibility
3. Malleability
4. Brittleness

Answer: (a) Hardness

Which method fails if both components of a mixture are equally soluble in the same solvent?

1. Filtration
2. Evaporation
3. Crystallisation
4. Decantation

Answer: (c) Crystallisation

A mixture of liquid A and solute B is heated. Which method ensures recovery of both A and B separately without any loss?

1. Evaporation
2. Crystallisation
3. Distillation
4. Magnetic separation

Answer: (c) Distillation

Which of these describes a compound, not a mixture or element?

1. Methane gas that contains only carbon atoms
2. Carbon dioxide formed by heating limestone
3. Sea water containing salts and dissolved gases
4. A lump of gold metal

Answer: (b) Carbon dioxide formed by heating limestone

The diagram shows the steps of a centrifugation experiment used to separate a mixture of different particles suspended in a liquid. After the tube is spun in the centrifuge (Step 4), three distinct layers (A, B, and C) are formed in Step 5. Which of the following best matches the correct identification of the layers A, B, and C formed after centrifugation?

1. A – Solute; B – Water vapour; C – Ice crystals
2. A – Supernatant (clear liquid); B – Lighter solids; C – Heavier solids
3. A – Heavy solid; B – Lighter solid; C – Water
4. A – Oil layer; B – Chemical precipitate; C – Dissolved salt

Answer: (b) A – Supernatant (clear liquid); B – Lighter solids; C – Heavier solids

The long horizontal tube labelled C is surrounded by cold water. What is the name and function of this part?

1. Condenser; condenses vapour into liquid
2. Funnel; separates liquids
3. Filter; removes impurities
4. Separator; divides immiscible liquids

Answer: (a) Condenser; condenses vapour into liquid

Which pair correctly matches one element and one compound from everyday life?

1. Oxygen and water
2. Salt and sugar
3. Milk and hydrogen
4. Air and iron

Answer: (a) Oxygen and water