February 2025

Selection

By |2025-02-12T08:59:43+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Selection

  • Each time male and female individuals reproduce they create an offspring that is different from themselves
  • This changes accrue over time to bring about much change in the descendants as there is inter-breeding between many individuals in each generation
  • This changes might result in the offspring having certain advantageous characteristics that are […]
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Experiment: to show changes in shape and volume of iodine crystals when they are heated

By |2025-02-12T09:11:39+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

sublimation_of_iodine-min

ZIMSEC O Level Combined Science Notes: An  experiment To show changes in shape and volume of iodine crystals when they are heated

Materials: evaporation dish/tin lid, glass filter funnel, burner, burner stand, one iodine crystal

Method

  1. Place the iodine crystal into an evaporation dish
  2. Put the filter funnel upside down over the crystal
  3. Warm the crystals […]
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Experiment:Making magnesium oxide compound

By |2025-02-12T09:20:23+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment:Making magnesium oxide compound

Aim: To make a compound of magnesium and oxygen (magnesium oxide)

Materials: magnesium ribbon, sandpaper, tongs, burner

Burning metals in air, Magnesium oxide. Burning metals in air, Magnesium oxide.

Method

  1. Clean a piece of magnesium ribbon with sandpaper
  2. Examine the magnesium and note its physical properties
  3. Hold the […]
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Experiment: Investigating the rusting of iron

By |2025-02-12T08:56:58+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Investigating the rusting or iron Investigating the rusting of iron ZIMSEC O Level Combined Science Notes: Experiment: Investigating the rusting of iron

Aim: Investigating the rusting (oxidation) of iron

Materials: 4 iron nails, 1 steel nail, a piece of copper/brass, 5 test tubes, cotton wool, solid calcium chloride, magnesium ribbon

Method

  1. Half fill two test tubes with […]
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Experiment: The rate of reactions and temperature

By |2025-02-12T09:16:26+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Relationship between temperature and rate of reaction. Image credit bu.edu Relationship between temperature and rate of reaction. Image credit bu.edu ZIMSEC O Level Combined Science Notes:Experiment: The rate of reactions and temperature

Aim:  To find the effect of temperature on the rate of reaction: using hydrochloric acid and sodium thiosulphate

Materials: flask, […]

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Coating metals/Protecting metals from corrosion

By |2025-02-12T09:31:18+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Investigating the rusting or iron Investigating the rusting or iron ZIMSEC O Level Combined Science Notes: Coating metals/Protecting metals from corrosion

  • Steel has many uses for example construction and to make utensiles
  • This is because it is cheap and strong
  • It is however susceptible to rusting
  • This is because it combines […]
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The Haber process and the Manufacture of Ammonia

By |2025-02-12T08:57:39+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

 ZIMSEC O Level Combined Science Notes: The Haber process and the Manufacture of Ammonia
  • Sable Chemicals produces ammonia at their Kwekwe plant
  • Ammonia is mainly used to make nitrogen fertilizers such as ammonium nitrate which are used in the agriculture industry
  • Ammonia is made using Hydrogen and Nitrogen
  • Hydrogen is obtained from electrolysis of water and
  • Nitrogen […]
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Fuel Engines

By |2025-02-12T09:12:54+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Most cars use fuel engine. Image credit ecurrent.fit.edu/blog/ Most cars use fuel engine. Image credit ecurrent.fit.edu/blog/ ZIMSEC O Level Combined Science Notes: Fuel Engines

  • A machine is a device that changes energy from one form to another
  • When the energy used by the machine is chemical energy the machine is called […]
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Resistors in parallel and in series

By |2025-02-12T09:28:08+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

fusion_title size=”3″ content_align=”left” style_type=”default” sep_color=”” margin_top=”” margin_bottom=”” class=”” id=””]ZIMSEC O Level Combined Science Notes:  Resistors in parallel and in series [/fusion_title]

  • Resistance in a series can be changed by placing more or less resistors in a circuit
  • The total resistance of resistors depends in the way in which they are arranged in the circuit
  • Resistors can be put in series or […]
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Electromagnetic Induction

By |2025-02-12T09:43:51+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Inducing a current using a magnet. Image credit youtube.com Inducing a current using a magnet. Image credit youtube.com ZIMSEC O Level Combined Science Notes: Introduction:Motors and generators

  • Electromagnetic induction- is the production of a voltage across an wires (electrical conductor )due to its dynamic interaction with a magnetic field.
  • If a magnet […]
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