February 2025

The production of Nitric acid

By |2025-02-12T08:58:32+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

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

  • Some of the ammonia produced using the Haber process is used in the production of nitric acid
  • The first stage in the process of making nitric acid is the oxidation of ammonia
  • To form nitric acid
  • \text{ammonia + oxygen} \rightarrow\text{nitric oxide+ water+heat}
  • This an exothermic reaction

    • […]

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The Petrol engine

By |2025-02-12T09:13:38+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Four Stroke Petrol Engine. Image credit petrolheadkenya.com Four Stroke Petrol Engine. Image credit petrolheadkenya.com ZIMSEC O Level Combined Science Notes: The Petrol engine

  • Four strokes are involved in the operation of most petrol engines
  • They are thus known as four-stroke engines
  • The first stroke is known as the inlet stroke
  • During the […]
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Experiment: Determining the resistance of resistors in parallel and in series

By |2025-02-12T09:29:49+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Resistors in series Resistors in series ZIMSEC O Level Combined Science Notes: Experiment: Determining the resistance of resistors in parallel and in series

Aim: To determine the combined resistance of resistors in series and in parallel

Materials: 4 cells, 2 bulbs/2 resistors, switch, ammeter, voltmeter, leads with crocodile clips

Method Resistors in [...] </p srcset=

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Experiment: Demonstrating how current is induced

By |2025-02-12T09:45:24+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: Experiment: Demonstrating how current is induced

Aim: To demonstrate electromagnetic induction

Materials: an electric coil (you can make one using varnished copper), galvanometer with a zero at the centre, connecting leads […]

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Investigating whether thick beams support more weight

By |2025-02-12T09:10:29+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Plasticine can be used to model cylinder beams. Image credit wordpress.com Plasticine can be used to model cylinder beams. Image credit wordpress.com ZIMSEC O Level Combined Science Notes: Experiment: Investigating whether thick beams support more weight

Aim: To show that thicker beams can support more weight

Materials: Plasticine/Stikistuff, wooden board, small cardboard cylinders 2cm in […]

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Experiment:To compare the effects of atmospheric corrosion on metals

By |2025-02-12T09:26:53+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Rusted metal. Image credit racingstrong.com Rusted metal. Image credit racingstrong.com ZIMSEC O Level Combined Science Notes: Experiment:To compare the effects of atmospheric corrosion on metals

Aim: To compare the effects of atmospheric corrosion on various metals

Materials:  samples of mild steel/cast iron, stainless steel, cutting steel (razor blade/old hacksaw blade), brass, aluminium, copper, plastic […]

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The concept of pressure

By |2025-02-12T08:59:22+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

 ZIMSEC O Level Combined Science Notes: The concept of pressure
  • Pressure is the force acting over an area
  • In such pressure is usually the force per unit area exerted by a fluid/gas
  • over a surface with which it is in contact
  • \text{Pressure=} \dfrac{Force}{Area}
  • If a big force is exerted over a small area it results high pressure
  • An example […]
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Contraception: The pill

By |2025-02-12T09:39:17+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit citifmonline.com Image credit citifmonline.com ZIMSEC O Level Combined Science Notes:Contraception: The pill

  • Are also known as birth control pills (BCPs) or
  • Oral Contraceptive Pills (OCPs)

How it works

  • They contain the two female hormones: oestrogen and progesterone
  • They prevent the release of ova/female sex cells
  • They cause growth of an […]
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Centralised Sewage Treatment Works

By |2025-02-12T09:06:37+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Sewage treatment works at Morton Jaffray,Harare. Image credit hararenews.co.zw Sewage treatment works at Morton Jaffray,Harare. Image credit hararenews.co.zw ZIMSEC O Level Combined Science Notes: Centralised Sewage Treatment Works

  • Are used to collect and treat sewage waste from large industrial and residential areas
  • They treat large quantities of human waste
  • The raw […]
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