Chapter 4 Practice Paper: Separation Techniques — question paper

Section A: Multiple-choice questions[10 marks]

Answer all questions. For each question, write the letter (A, B, C or D) of the correct answer in the brackets provided.

1. 1

   Tea leaves stay in a strainer while the drink drips into a cup. The leaves left in the strainer are the

   1. Aresidue.
   2. Bfiltrate.
   3. Csolvent.
   4. Ddistillate.
   ( )
2. 2

   Which method both evaporates a solvent and condenses it so the liquid can be collected?

   1. Afiltration
   2. Bchromatography
   3. Cdistillation
   4. Dusing a magnet
   ( )
3. 3

   Paper chromatography is used to

   1. Apick up iron.
   2. Bseparate dissolved dyes.
   3. Cmeasure a volume.
   4. Dcondense steam.
   ( )
4. 4

   A magnet will not separate aluminium cans from sand because aluminium is

   1. Aa gas.
   2. Bdissolved.
   3. Cthe filtrate.
   4. Dnot magnetic.
   ( )
5. 5

   Salt crystals are wanted from salt solution, and the water can be lost. The method is

   1. Aevaporation.
   2. Bfiltration of the dissolved salt.
   3. Cchromatography.
   4. Dmagnetic attraction.
   ( )
6. 6

   A cook pours noodle water through a cloth. The cloudy liquid that collects in the bowl underneath is the

   1. Aresidue.
   2. Bmagnet.
   3. Cfiltrate.
   4. Dspot.
   ( )
7. 7

   Filtration does not remove dissolved salt from water because the salt

   1. Ais magnetic.
   2. Bis a gas only.
   3. Cturns into sand.
   4. Dis dissolved and passes through the paper.
   ( )
8. 8

   In distillation, the condenser is used to

   1. Afilter sand.
   2. Bcool the vapour so it becomes liquid.
   3. Cdraw a start line.
   4. Dmagnetise the salt.
   ( )
9. 9

   A student draws the starting mark for a felt-tip test with a ballpoint pen. The chromatogram is spoiled because

   1. Athe pen ink dissolves and travels, adding extra colours.
   2. Ba pen mark is a solvent.
   3. Ca pen mark is magnetic.
   4. Dpencil would have dissolved faster than the felt-tip ink.
   ( )
10. 10

    Distillation can produce drinking water from sea water because

    1. Asand is magnetic.
    2. Bsalt evaporates and water stays in the flask.
    3. Cwater evaporates and is condensed, while the salts stay behind.
    4. Dchromatography removes the salt.
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. Show your working for calculations.

1. 1

   A jar from a beach clean-up contains gravel, dissolved sugar from a spilled drink, and water.

   1. (a)

      Describe how to collect dry gravel from this jar.

      [2]
   2. (b)

      Describe how to collect solid sugar from the liquid that passed through.

      [2]
   3. (c)

      The class wants to keep the water as well as the sugar. State why they should distil the liquid instead of only evaporating it.

      [2]
2. 2

   A forensic team compares the ink in a ransom note with three pens, using paper chromatography.

   1. (a)

      State why the baseline under the ink dots must be pencil, not the pen being tested.

      [1]
   2. (b)

      State where the solvent level must be, relative to the ink spot.

      [1]
   3. (c)

      The ink gives a blue spot and a yellow spot at different heights. Explain what this shows.

      [2]
   4. (d)

      The note’s ink matches pen 2 and not pens 1 or 3. State what the matching pattern of spots allows the team to conclude.

      [1]
3. 3

   A scrap heap contains iron nails and aluminium cans, both mixed with dry sand.

   1. (a)

      State how the iron nails can be removed.

      [1]
   2. (b)

      Explain why the same magnet does not remove the aluminium cans.

      [2]
   3. (c)

      Explain why filtration cannot remove salt that is dissolved in a bucket of water nearby.

      [2]
4. 4

   Singapore has a limited supply of fresh water.

   1. (a)

      State one reason fresh water is treated as a precious resource.

      [1]
   2. (b)

      Name one separation method used to obtain water from sea water.

      [1]
   3. (c)

      State two ways a student can use less water at home.

      [2]