RAS Mains Paper 2

Allotropes of carbon Allotropy is the property of some chemical elements to exist in two or more different forms, or allotropes, when found in nature. There are several allotropes of carbon. Diamond Diamond is probably the most well known carbon allotrope. The carbon atoms are arranged in a lattice, which is a variation of the … Read more Allotropes of carbon

Acid An acid is a substance which forms H+ ions as the only positive ion in aqueous solution. Examples:- Hydrochloric acid dissolved in water forms H+ and Cl– ions HCl —> H+ + Cl–   Sulphuric acid dissolved in water forms H+ and SO42- ions H2SO4 —>2H+ + SO42-   Nitric acid forms H+ and NO3– ions when dissolved in water HNO3 —> H+ + NO3–   … Read more pH Scale and importance of pH in daily life

Corrosion is defined as an attack on a material as a result of chemical, frequently electrochemical reaction, with the surrounding medium. According to this definition, the term corrosion can be applied to all materials, including non-metals. But in practice, the word corrosion is mainly used in conjunction with metallic materials. Why do metals corrode? Apart … Read more Corrosion and its prevention

Catalyst Catalyst, in chemistry, any substance that increases the rate of a reaction without itself being consumed. Enzymes are naturally occurring catalysts responsible for many essential biochemical reactions. Most solid catalysts are metals or the oxides, sulfides, and halides of metallic elements and of the semimetallic elements boron, aluminum, and silicon. Gaseous and liquid catalysts … Read more Catalyst

Soap – Characteristics And Uses Soaps are excellent cleansing agents and have good biodegradability. A serious drawback which reduces their general use, is the tendency for the carboxylate ion to react with Ca+ and Mg+ ions in hard water. The result is a water insoluble salt which can be deposited on clothes and other surfaces. These … Read more Soap and Detergents – Cleansing action of soap.

A molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass is called a polymer. A polymer  is a large molecule, or macromolecule, composed of many repeated subunits. Due to their broad range of properties,both synthetic and … Read more Polymers and their uses

Digestive System Introduction The respiratory and circulatory systems work together to provide cells with the oxygen they need for cellular respiration. Cells also need glucose for cellular respiration. Glucose is a simple sugar that comes from the food we eat. To get glucose from food, digestion must occur. This process is carried out by the … Read more Digestive System

Respiratory System Introduction Red blood cells are like trucks that transport cargo on a highway system. Their cargo is oxygen, and the highways are blood vessels. Where do red blood cells pick up their cargo of oxygen? The answer is the lungs. The lungs are organs of the respiratory system. The respiratory system is the … Read more Respiratory System

Circulatory System The circulatory system can be compared to a system of interconnected, one-way roads that range from superhighways to back alleys. Like a network of roads, the job of the circulatory system is to allow the transport of materials from one place to another. As described in Figure below, the materials carried by the … Read more Circulatory System

Excretory System Introduction If you exercise on a hot day, you are likely to lose a lot of water in sweat. Then, for the next several hours, you may notice that you do not pass urine as often as normal and that your urine is darker than usual. Do you know why this happens? Your … Read more Excretion system of man and excretion process