Introduction Air, water, soil, coal, petroleum, natural gas and minerals are obtained directly from nature; therefore, they are known as natural resources. Plastics, synthetic fibres, steel, drugs, and explosives are all manufactured by man. Anything in the environment which can be used is called a resource. Natural resources can be broadly classified into two kinds: …
Introduction Fabrics are made from fibres obtained from natural or artificial sources. Fibres are also used for making a large variety of household articles. Natural fibres like cotton, wool, silk, etc., are obtained from plants or animals. Synthetic fibres, on the other hand, are made by human beings. That is why these are called synthetic …
Introduction They are living organisms of very small size. They are so small that they cannot be seen by the naked eye. We would require a microscope or magnifying glass to see them. Example: Bacteria, Fungi There are four major groups: Bacteria Fungi Protozoa Algae Viruses are also microscopic but are quite different from other …
Class 8 Chapter 2 Microorganisms: Friends and Foe Read More »
Introduction To provide food for a large population regular crop production, proper management and distribution are required. When the same type of plant is grown in one place on a large scale, it is called a crop. Depending on the seasons in India, there are two primary types of crops: Kharif Crops: The crops which …
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INTRODUCTION The principles of chemistry have been used for the benefit of mankind. Think of cleanliness — all the materials like soaps, detergents, household bleaches, toothpaste, etc. will come to your mind: all these are products of chemistry. Take a look at the beautiful clothes — immediately chemicals of the synthetic fibres used for …
INTRODUCTION The word ‘polymer’ is composed of two Greek words: poly means many and mer means units or parts. Polymers are very large molecules with high molecular mass (103 -107u). These are also referred to as macromolecules, which are formed by the joining of repeating structural units on a very large scale. The repeating …
INTRODUCTION The main feature of a living system is that it grows, sustains and reproduces itself. The most amazing thing about a living system is that it also comprises non-living atoms and molecules. The detailed knowledge of chemical reactions taking place within a living system falls in the domain of biochemistry. Living systems are …
INTRODUCTION Amines form an important class of organic compounds which are derived by replacing one or more hydrogen atoms of ammonia molecules by alkyl/aryl group(s). In nature, they are found among proteins, vitamins, alkaloids and hormones. Synthetic examples include polymers, dyestuffs and drugs. Adrenaline and Ephedrine, are two biologically active compounds, both of which …
INTRODUCTION In aldehydes, the carbonyl group is bonded to a carbon and hydrogen whereas, in the ketones, it is bonded to two carbon atoms. The carbonyl compounds in which carbon of the carbonyl group is bonded to carbon or hydrogen and oxygen of hydroxyl moiety (-OH) are known as carboxylic acids, while in compounds …
Class 12 Chapter 12 Aldehydes, Ketones and Carboxylic Acids Read More »
