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CHEMISTRY Marking Scheme - Form 1 End of Term 1 2019 Examinations

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Click the link below to download the full 2019 Form 1 Term 1 Past Papers pdf document, with all the topics.

https://downloads.easyelimu.com/details/78-2019_Form_1_Term_1_Past_Papers

  1.  
    • Luminous                             Non Luminous
    • It’s sooty                               Not sooty
    • Not very hot                           Very hot
    • Not steady                              Steady
    • Large and wavy                       Small and straight
    • Has four zones                         has three zones
    • Not noisy                                 Noisy
  1.  
    • A- Pale blue
      B- Green blue zone
      C- Almost colourless zone
  2.  
    1. A drug is any substance natural or manufactured which when used after the way the body functions.
    2. Lung cancer, Liver Cirrhosis, mental disorders, respiratory complications, addiction and     dependency.
  1.  
    • Never taste anything in the laboratory
    • Never run while in the laboratory
    • Label all the chemicals
  1. Medicine, Agriculture, Geology, Engineering,Food Industry and any appropriate career (1mk)
  2. DIAGRAM
    chromatograph
  1.  
      • R- Melting
      • V- Boiling/ Vaporisation
      • W- Condensation
      • U- Freezing
    1. Iodine, Solid Carbon (iv) Oxide, benzoic acid, aluminium Chloride, iron (iii) Chloride (any two for (2mk)
  1.  
    1.  
      • Heat water steadily
      • Thermometer should not touch the beaker
      • Stir the naphthalene continuously.
    2.  
      1. Determine the temperature.
      2. Stir the naphthalene so as to distribute heat evenly.
      3. Transfer heat to naphthalene so as to melt it.
  1.  
      • Deflagrating spoon
        To heat/burn solid substances.
    1.  
      • Beaker
      • Conical flask                   diagram   ½ mk     naming   ½ mk
      • Volumetric flask
      • Syringe
      • Pipette
      • Burette
  2.  
    1. Separating funnel
    2. B
    3.  Decanting or sucking top of liquid into another container or using teat pipette.
  3.  
    1. A combination of two or more substances which are not chemically combined or A combination of two or more substances in which the individual components retain their chemical and physical properties.
    2.  
      1. Iron and sulphur, iodine and common salts alloys ( any suitable mixture)
      2. Sand and water, salt and water
      3. Water and Paraffin, water and ethanol.
  4.  
    1. A conductor is a substance that allows electrical energy to pass through it.
    2.  
      1. Conductor
      2. Non- Conductor
  5.  
    1. Observation, Analysis, interpretation, making conclusion, collection of data
    2. Glass industry, petroleum, pharmaceutical or drug industry, plastic, detergent industry/cosmetics iron and steel, fertilizers.
  6.  
    1. When the air hole is open.
    2. The dark regions are due to the hotter pale blue region, while the middle region is unburnt because it was in contact with the region of unburnt gases.
      burnt splint.jpg
  1.  
    1. Flammable - Meaning substance catches fire easily
    2. Explosive - Meaning substance may explode if ignited
  1.  
    1. To increase the surface area in contact with the solvent
    2. Water cannot dissolve oil
    3. Solvent extraction
  1.  
    1. Temperature remains constant until all the naphthalene melts. Heat supplied is used to weaken the forces of attraction holding naphthalene particles together
    2. Pure, It has a sharp melting point.
    3. Temperature increases steadily as naphthalene absorbs heat, which increases the particles making the particles vibrate more vigorously.
  1.  
    1.  
      • Temporary physical                                                   Temporary chemical
      • No change in mass                                                       mass change
      • No new substance formed                                             new substance is formed
      • No net heat change                                                      there is net heat change
    2. Formation of colourless droplets on cooler parts blue crystals turn to white powder.
    3. Chemical Change
  1.  
    1.  
      1. P- fractionating column
      2. Q- wire gauge
    2.  
      • The tubing coming from the distillation flask should not be immersed in the mixture.
      • The thermometer should be placed above the glass beads in the fractionating column.
      • The delivery tube coming from the boiling tube should begin at the top level of the glass beads.
  1. Drugs bought at a pharmacy or a retail shop without written instructions from a doctor.
  1.  
    1. To avoid the loose clothing catching fire.
    2. To avoid the liquid or solid from spurting out and causing injury to the observer
  2.  
    1. Anything that has mass and occupies space. (2mk)
    2.  
      • Gases
      • Solids
      • Liquids
  3.  
    1.  
      • E- Chimney
      • F- Collar
      • G- Base
      • To regulate the amount of air entering the chimney.
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