February 2025

The respiratory system and gaseous exchange

By |2025-02-12T09:34:21+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Human respiratory system. Image credit anatrik.org Human respiratory system. Image credit anatrik.org ZIMSEC O Level Combined Science Notes: The respiratory system and gaseous exchange

  • The respiratory system is responsible for gaseous exchange and breathing so that oxygen is taken into the body and carbon dioxide is released from the body.
  • Mammals including […]
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Experiment: Investigating the conditions necessary for germination to occur

By |2025-02-12T09:33:39+02:00February 12th, 2025|Notes, O Level Shona Notes, Ordinary Level Notes|

germination_of_seeds

ZIMSEC O Level Combined Science Notes: Reproduction in plants: Reproduction in Plants: Investigating the conditions necessary for germination to occur  

Materials: maize/bean seeds, containers one of which has a lid, cotton wool, filter paper, pyrogallic acid

Method

  1. Take four batches with ten seeds in each batch
  2. Put them in containers as shown in the diagrams above […]
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Variation

By |2025-02-12T08:59:05+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Variation in chillies. Image credit chilipapryczka.pl Variation in chillies. Image credit chilipapryczka.pl ZIMSEC O Level Combined Science Notes: Variation

  • The living world has many thousands of different types of plants and animals
  • For example lions are different from hyenas which in turn are different from say goats
  • In plants the Msasa trees are […]
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Experiment: to show that solids change shape when they melt

By |2025-02-12T09:11:07+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Melting wax takes up the shape of the container. Image credit about.com Melting wax takes up the shape of the container. Image credit about.com ZIMSEC O Level Combined Science Notes: An  experiment to show that solids change shape when they melt

Materials: tin lid/evapouration dish, burner, burner stand, candle wax

Method

  1. place […]
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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: Reducing Copper oxide with carbon

By |2025-02-12T09:46:06+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment: Reducing Copper oxide with carbon

Aim: To reduce copper oxide with carbon

Materials: black copper oxide, tongs, crucible lid, powdered carbon, burner

Carbon can be used to reduce copper oxide Carbon can be used to reduce copper oxide

Method

  1. Mix the copper oxide and powdered carbon together in the crucible […]
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Experiment: Investigating the effects of concentration on marble chips

By |2025-02-12T09:15:36+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Concentration varies directly with the rate of reaction Concentration varies directly with the rate of reaction ZIMSEC O Level Combined Science Notes: Experiment: Investigating the effects of concentration on marble chips

Aim: To investigate the effect of concentration on the reaction between marble chips and hydrochloric acid

Materials : conical flask/glass jam jars, measuring cylinder, […]

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Experiment: Separating copper from its oxides

By |2025-02-12T09:30:43+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment: Separating copper from its oxides

Aim: To separate copper from its oxide ores

Materials: copper oxide, iron nail, dilute sulphuric acid, filter funnel, 2 beakers, stirring rod, filter paper, burner

Extracting copper from copper oxide Extracting copper from copper oxide

Method

  1. Place a small amount of copper oxide in a […]
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The Manufacture of sulphuric acid

By |2025-02-12T08:56:03+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: The production of sulphuric acid

  • Sulphuric acid is produced using the Contact process
  • In Zimbabwe there is a sulphuric acid production plant at Zimphos in Harare
  • Sulpher or iron pyrites (iron sulphide) is roasted to form sulphur dioxide
  • The word equation for roasting iron pyrites is:
  • \text{iron sulphide+oxygen}\rightarrow\text{iron oxide+sulpher dioxide}
  • The word […]
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