INT SCI G 9 OPENER TERM 3 2026 MS (1)

KENYA JUNIOR SCHOOL EDUCATION ASSESSMENT

INTEGRATED SCIENCE GRADE 9

MARKING SCHEME

1. (a) Substances used to prepare oxygen in the laboratory:(2 mks)

[i] Hydrogen peroxide (and Manganese (IV) oxide catalyst)[ii] Potassium chlorate (or Potassium permanganate / Sodium peroxide / Water)(1 mark each for any two correct substances)

1. (b) Function of Manganese (IV) Oxide during the preparation of oxygen:(1 mk)

It acts as a catalyst to speed up the decomposition of hydrogen peroxide without being consumed in the reaction. (1 mark)

1. (c) Test for oxygen in the laboratory:(2 mks)

Relights / rekindles a glowing splint introduced into a gas jar of oxygen. (2 marks)

1. (d) Chemical properties of oxygen:(3 mks)

[i] Supports combustion / burning.[ii] Neutral to litmus paper (neither acidic nor basic).[iii] Reacts with metals to form basic metallic oxides (e.g., 2Mg + O₂ → 2MgO).[iv] Reacts with non-metals to form acidic non-metallic oxides (e.g., C + O₂ → CO₂).(1 mark each for any three correct chemical properties)

2. (a) Classes of fire and their causes:(4 mks)

[i] Class A: Fires involving solid organic combustibles (e.g., wood, paper, textiles, plastics).[ii] Class B: Fires involving flammable liquids or meltable solids (e.g., petrol, diesel, oil, paints, paraffin).[iii] Class C: Fires involving flammable gases (e.g., LPG, butane, propane, methane, hydrogen).[iv] Class D: Fires involving combustible metals (e.g., magnesium, titanium, potassium, sodium).(1 mark for each class correctly stated with its cause/fuel source)

2. (b) Hazard Symbol and Meaning Matching Table:(4 mks)

Symbol Description / Icon

Meaning