Rounding off numbers
To ’round off’ or ‘approximate’ a number to a desired degree of accuracy, we

round the number up if the next digit is 5 or more
round the number down if the next digit is less than […]

Introduction
The method of solving “by substitution” works by solving one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other […]

What is Matter?
Matter is anything that has mass and occupies space. There are 3 states of matter, solids, liquids and gases. Examples of matter include the plants animals around us, the food we eat, the water we […]

Introduction
Fats and oils are naturally-occurring esters of three long carboxylic acids  called fatty acid with a special type of alcohol called glycerol ( propane- 1,2,3-triol). Glycerol has three carbon […]

Mean Deviation
This is the average sum of the deviations from the arithmetic mean (i.e. the sum of the differences between the scores and the mean) divided by the total frequency.
Example 1
Find the mean […]

Introduction
A machine is essentially a device or tool which allows a force (or effect) applied at one point to overcome a resisting force (or load) at another point.
Consider a simple machine such as a screw. […]

Introduction
Electrochemistry is the study of electricity and how it relates to chemical reactions. In electrochemistry, electricity can be generated by movements of electrons from one element to another in a […]

Substitution Methods
The method of solving “by substitution” works by solving one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the […]

Introduction
Viscosity simply means friction in fluids.
It is observed that it is easier to pour water or kerosene from a container than to pour honey or engine oil. A little stone dropped into a cylinder of […]

Introduction
In everyday life, the term work is applied to any form of activity that requires the exertion physical or mental effort, someone may say ‘I go to work’, another may say ‘I work in the office of the d […]

Introduction
Alkanoic acids are also known as carboxylic acids. A carboxylic acid can he identified from the carboxyl functional group and the ‘-oic’ name ending.

Structural Examples of carboxylic […]

Standard Index Form
Standard index form is also known as standard form. It is very useful when writing very big or very small numbers.
In standard form, a number is always written as: a × 10 n
a is always […]

Introduction 
In chemistry, quantitative laws used to express magnitudes of electrolytic effects, first described by the English scientist Michael Faraday in 1833. The quantities of substances produced or […]

Resistivity
Resistivity: The resistance of a wire or material conductor maintained at a constant temperature is related to its length (l) and its cross-sectional area (A) by the expression
R = ρ l/A
Where ρ i […]

Introduction
We define the notation 22 as “two squared” or the square of two” or “two raised to the power of 2” and it means 2 x 2.
i.e. 22 = 2 x 2 (i.e. 2 multiplied by itself in 2 places ) also 23 = 2 x 2 x 2 […]

Introduction

Electrons
Electrons were discovered by Sir John Joseph Thomson in 1897 in his cathode ray experiment. He subjected residual gas to a high potential difference at a very low pressure. He observed […]

Concept of Equilibrium: Dynamic and Static Equilibrium
An object is in equilibrium when it is not accelerated, that is, there is no net force acting on it in any direction. For such a body in equilibrium, the […]

Directed Algebraic Terms
Remember that in algebra, letters stand for numbers. The number can be whole or fractional, positive or negative.

Just as 5a is short for 5 x a, so -5a is short for (-5) x a.
Just […]

IUPAC Nomenclacture of Inorganic Compounds and Concept of Oxidation Number
Oxidation number is the charge on the valency of an element, i.e.
Oxidation state = Valency + Charge
The valency of metal carries a […]

Introduction
Equal volumes of different substances have different masses or weights. For example 1 m3 of lead weighs differently from 1 m3 of wood. Also 1 m3 of water has a weight different from that of sulphuric […]