February 2025

Pesticide Warning Symbols

By |2025-02-12T09:09:54+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit incomdirect.com Image credit incomdirect.com ZIMSEC O Level Combined Science Notes: Pesticide Warning Symbols

  • Pesticides are graded according to their toxicity i.e.
  • According to how harmful they are to humans.
  • Every pesticide must have a label that clearly shows its “danger” level show.
  • There are four common danger levels of chemicals.

Purple […]

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Experiment: Is energy released by germinating seeds?

By |2025-02-12T08:56:39+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Germinating seeds. Image credit hummert.com Germinating seeds. Image credit hummert.com ZIMSEC O Level Combined Science Notes: Experiment: Is energy released by germinating seeds?

Aim:  Determine whether energy is released when seeds are germinating.

Hypothesis: Seeds are structures produced by plants (living organisms). They respire when they are germinating.

Materials: tow insulated containers/vacuum flasks, two supporting […]

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The mammal heart

By |2025-02-12T09:20:21+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The structure of the human heart. The structure of the human heart. ZIMSEC O Level Combined Science Notes: The mammal heart

  • Is made up of muscle which contracts continuously throughout the mammal’s life.
  • The number of contractions differ from mammal to mammal
  • In elephants it contracts about 25 times/minute
  • In humans it contracts about 70-80 […]
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The physical components of the soil

By |2025-02-12T09:40:16+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Loam soil. Image credit betterground.org Loam soil. Image credit betterground.org ZIMSEC O Level Combined Science Notes: The physical components of the soil  

  • Soil is made up of rock/soil particles
  • Some soils are easy to compress because they have air in them
  • Soils are usually moist
  • Soils also have dissolved minerals in them

Sand, Loam and […]

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An introduction to Beams and their types

By |2025-02-12T09:45:45+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

beams_introduction-min Common types of beams and their associated forces ZIMSEC O Level Combined Science Notes: An introduction to Beams and their types

  • A beam is any material that is supported so that it can hold a load
  • A simple beam is a length of material e.g steel supported along its length so that […]
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The reactions of metals and water

By |2025-02-12T09:34:49+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: The reactions of metals and water

  • Water is a compound of oxygen and hydrogen
  • When metals react with water they remove the oxygen from the water
  • We say the metals displace the hydrogen from the water
  • A metal oxide is formed
  • Freeing up the oxygen
  • The following word equation summarizes the nature of […]
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Experiment: The corrosion of metals by acids

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

ZIMSEC O Level Combined Science Notes: Experiment: The corrosion of metals by acids

Aim: Investigating the corrosion of some metals by acids

The corrosion of metals by acid gives off hydrogen gas The corrosion of metals by acid gives off hydrogen gas

Materials: 5 test tubes, dilute hydrochloric acid, granulated zinc, iron fillings/iron nail, copper foil, […]

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Extraction of iron: The blast furnace

By |2025-02-12T09:21:45+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Extraction of iron: The blast furnace

  • After iron ore is mined it is send to the blast furnace
  • Iron is extracted from its ore in a blast furnace

 

The structure of a blast furnace. Image credit s-cool.co.uk The structure of a blast furnace. Image credit s-cool.co.uk

    […]
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Experiment Chrome plating a nickel cathode

By |2025-02-12T09:36:06+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Nickel and Chrome plate. Image credit 1911forum.com Nickel and Chrome plate. Image credit 1911forum.com ZIMSEC O Level Combined Science Notes: Experiment Chrome plating a nickel cathode

Aim: To chrome plate a nickel cathode

Materials: nickel-plated  electrode, lead electrode, beaker, chromic acid

Method

  1. Set up an electrolytic cell using a nickel plated cathode from this […]
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