O Level Science Notes Archives - Page 5 of 33 - Free ZIMSEC & Cambridge Revision Notes

Safety when using chemicals

By garikaib|2025-02-12T09:09:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Safe use of chemicals. Image credit montana.edu ZIMSEC Combined Science Notes: Safety when using chemicals

Pesticides are almost always harmful to human beings.
They are graded according to their level of toxicity i.e. how dangerous they are to humans.
There are no safe pesticides all are […]

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Inhaled vs Exhaled air experiment: Method 2

By garikaib|2025-02-12T09:40:39+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Lime water is used to test for carbon dioxide. Image weebly.com ZIMSEC O Level Combined Science Notes: Inhaled vs Exhaled air experiment: Method 1

Aim: Test to compare the composition of exhaled and inhaled air.

Materials: Limewater (to test for the presence […]

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Food types and their importance

By garikaib|2025-02-12T09:11:37+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Different types of food have different functions. Image credit healthydietadvisior.com ZIMSEC O Level Combined Science Notes: Food types and their importance

Carbohydrates-these are energy-rich foods that are largely made up of starch and sugars. They are easily broken down in the […]

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Experiment: Growing plants using the vegetative reproduction method

By garikaib|2025-02-12T09:37:05+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Growing mulberry cuttings. Image credit wordpress.com ZIMSEC O Level Combined Science Notes: Reproduction in plants: Growing plants using the vegetative reproduction method

Materials; trays of soil/sand or prepared garden beds, plant cuttings of sugar cane, mulberry, sweet potato cuttings etc

Method Plant [...]
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Breeding

By garikaib|2025-02-12T09:00:32+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

SeedCo trial fields are used for breeding seeds. Image credit seedco.co ZIMSEC O Level Combined Science Notes: Breeding

Controlled breeding in livestock and crops allow farmers to obtain animals and crops with the best characteristics
Each breed or variety has is […]

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Experiment: The heating curve of water

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

The heating curve of water. Image credit wordpress.com ZIMSEC O Level Combined Science Notes: Experiment: The heating curve of water

Materials: beaker, crushed ice, thermoter, burner, clock/watch with a stop watch function

Method

Half fill a beaker with crushed ice
Record the temperature of the ice
Place […]

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Properties of Nonmetals vs metals

By garikaib|2025-02-12T09:21:43+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Common metal objects. Image credit blogspot.com ZIMSEC O Level Combined Science Notes: Experiment: Properties of Metals and Non-Metals

Elements can be divided into two groups:
Metals and Non-metals
Examples of metals are: copper, zinc, iron, gold, silver, chrome, lead and tin
Almost all metals have certain properties that makes them […]

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Differences between reduction and oxidation
Gallery
Differences between reduction and oxidation

Notes, O Level Science Notes, Ordinary Level Notes

Differences between reduction and oxidation

By garikaib|2025-02-12T08:57:47+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Differences between reduction and oxidation

There are differences between oxidation and reduction
The table below shows the differences between oxidation and reduction:

Often reduction and oxidation occur in conjunction
That is at the same time and during the same reaction
For example:
\text{ammonia+oxygen}\rightarrow\text{water+nitrogen dioxide}
Nitrogen gains oxygen and losses hydrogen […]

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Experiment: The effects of a catalyst on the rate of a reaction

By garikaib|2025-02-12T09:17:07+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Copper (II) can be used as a catalyst. Image credit chemistry-reference.com ZIMSEC O Level Combined Science Notes: Experiment: The effects of a catalyst on the rate of a reaction