Preparation of salts depends on the physical and chemical properties of the salt. For example, when choosing the best method to prepare a salt you need to consider the following: is the salt soluble? If yes, we usually prepare it…
This is a list of commonly asked uses of substances in O level Chemistry and Combined Science exams. Uses of oxygen Medical purposes – In hospitals, oxygen is given to some people who are injured or ill with disease that…
Writing balanced chemical equations is one of the most challenging aspects of O level chemistry. O level Chemistry fundamentally revolves around calculations, symbols and formula of chemical substances. This tutorial is about balancing chemical equations but before we start balancing…
Ionisation of elements Ionisation of Group 1 elements (alkaline metals) Atoms of Group 1 elements have 1 electron in the outer shell, so they ionise by losing 1 electron to form a positively charged ion of charge +1. This is…
Valence electrons are outer shell electrons of an atom. They participate in the formation of a chemical bond, if the outer shell of the element is not full. Valency electrons of the first 20 elements Electrons of the first 20…
Properties of hydrogen gas colourless odourless tasteless slightly soluble in water neutral to litmus lightest known gas 14.4 times less denser than air highly flammable Test for hydrogen gas Ignite the gas with a burning splint and it burns with…
Writing chemical formula and naming chemical compounds are some of the things O level chemistry students find challenging. This post is all about addressing the challenges faced by students when writing chemical formula and naming chemical compounds. Naming binary ionic…
Welcome to your comprehensive revision notes on methods of contraception and contraceptives! Understanding how to prevent pregnancy is crucial for responsible sexual health. There are various methods of contraception available, each with its own way of working and level of…
Welcome to your comprehensive revision notes on human reproduction, covering sex cells, fertilisation, pregnancy, the placenta, and child care. These stages are fundamental to understanding how humans reproduce and ensure the survival of their offspring. Let’s explore each of these…
Welcome to your comprehensive revision notes on the functions of human reproductive organs! The reproductive system is essential for the continuation of the human species. In this note, we will explore the specific roles of the various organs in both…
