Volume-9 General Science & Technology PDF

Rajasthan Public Service Commission Volume - 9 General Science & Technology S.No. Chapter Name Page No. 1. Chemistry in everyday life 1 S...

Rajasthan Public Service Commission Volume - 9 General Science & Technology S.No. Chapter Name Page No. 1. Chemistry in everyday life 1 States of Matter Solids Liquids Gas Cause of different physical states of matters Other states of matter Atomic Structure Electron Protons Neutrons Properties of electrons, protons, and neutrons Distribution of Electrons in Distinct Shells Valency Atomic Number (Z) Mass Number (A) Isotopes Isobars Metals, Non- metals and Metalloids Metallurgical Principles and methods Steps in Metallurgical Process Principles of Metallurgy Important ores and alloys Acids, Bases and Salts Acids Bases Strength of Acid and Bases Universal Indicator Salts Equations of Acids, Bases and Salts: Concept of pH and Buffers Buffers Important Drugs (Synthetic and Natural) Antacids Antihistamines Neurologically Active Drugs: Tranquilizers Antioxidants and Preservatives Insecticides Pesticides Fungicides Herbicides Fertilizers Binders and Sweeteners Carbon and its compounds Radioactivity - concepts and applications 2. Physics in everyday life 33 Gravitation Human eye and Defects Heat Magnetism Sound Electro- Magnetic Waves Nuclear fission and Fusion 3. The Cell 47 Excretory System Respiratory System Circulatory System Digestive systems in Human beings Blood groups Composition and Functions of blood Hormones Genetics and Lifestyle Diseases Human diseases- Communicable and Non-communicable Endemic, Epidemic, Pandemic their Diagnosis and Control Immunisation and Vaccination Drugs and Alcohol abuse Plant parts and their functions Plant nutrition Plant growth regulators Sexual and asexual reproduction in plants Important medicinal plants with special reference to Rajasthan 4. Basic Computer Science 96 Networking and its Types Frequency spectrum/ Electromagnetic Spectrum Benefits of Social Media Challenges 5. Scientific and Technological Advancements 117 Contribution of Indian Scientists in Science and Technology Radio-frequency identification (RFID) Technology Development of Science and Technology in Rajasthan Government Policies related to Science and Technology 6. Space Technology 140 Fundamentals Indian Space programme Satellite and their orbits Launch Vehicles Remote sensing Space Organizations: 7. Defence Technology 152 Regulatory Authorities Missiles Submarines Chemical and Biological weapons 8. Biotechnology and Genetic Engineering 167 Relevance mRNA Technology 9. Food and Nutrition 180 Food Macronutrients Fat Soluble Vitamins 10. Environment and Ecological changes and its impacts 189 Desertification Deforestation Climate Change Global Warming Ozone Depletion (UNEP) Coral Bleaching International Organizations, Programmes and Conventions on Climate Change Climate Change Protocols  1 Chemistry in everyday life CHAPTER States of Matter Solids Matters which have fixed volume and shape. Eg - stone, wood, brick, ice, sugar, salt, coal, etc. All metals are solid except mercury and gallium. Properties of solids Fixed volume. Fixed shape. High density. Heavy. Do not flow. Liquids Matters which have fixed volume but indefinite shape. Eg - milk, water, petrol, kerosene, alcohol, oil, etc. Since liquid can flow, it is also called fluid. Properties of liquids Definite volume. No definite shape. Get the shape of container in which they are kept. 1  Cannot be compressed much. Have less density compare to solid. Lighter than solid. Liquids flow and hence are called fluids. Gas Matters which have indefinite shape and volume. Eg - air, oxygen, hydrogen, nitrogen, carbon- dioxide, etc. Properties of gases Indefinite shape No fixed volume. Get the shape and volume of container. Fill the container completely. Have very low density. ○ So, gases are light. Can flow easily and hence are called fluids. Cause of different physical states of matters The physical states of matter depend upon three main factors: The force of attraction between particles. The space between the particles. The kinetic energy of particles. Solids The force of attraction between the particles of solids is very strong. There are minimum spaces between the particles of solids. The particles of solids have minimum kinetic energy. Because of great force of attraction particles of solids are closely packed together. ○ This makes the space between particles of solids almost negligible. The lowest kinetic energy of particles is not able to move the particles of solids. Hence, the great force of attraction and least space between particles of solids and lowest kinetic energy of particles keep the particles at fixed places. Because of the combination of these characters matter exists in solid state. Liquids The force of attraction between particles is strong but less strong than solids. The space between particles is more than that of solids but not less than liquids. The kinetic energy of particles is greater than solid. Strong force of attraction keeps the particles of liquids packed together. ○ But the force of attraction between particles of liquids is less strong than that of solid. ○ Because of this particles of liquids are loosely packed compared to solid. The kinetic energy of particles of liquids is greater than that of solids. Because of more space between particles and more kinetic energy than solids the particles of liquids slide over one another. These characters make a matter to exist in liquid state. Liquid can flow because its particles can slide over one another. 2 Gases The force of attraction between particles of gas is almost negligible. The space between particles of solid is greatest. The particles of gases have the greatest kinetic energy. ○ Because of negligible force of attraction the particles of gases are loosely packed consequently there are lots of spaces between their particles. ○ Because of the greatest kinetic energy the particles of gas move with high speed. Because of negligible force of attraction between particles and greatest kinetic energy the particles of gas have a tendency to escape out. ○ Because of these characteristics a matter exists in gaseous state. A matter exists in solid state because of the greatest force of attraction between its particles which makes the particles closely packed. A matter exists in liquid state because of less force of attraction between its particles than a solid, which makes the particles closely packed but allow them to slide over one another. A matter exists in gaseous state because of an almost negligible force of attraction between its particles, which is unable to keep the particles bonded together. Other states of matter Plasma Fourth state of matter. Similar to gas. Particles of plasma are made of free electrons and ions. Do not have a definite shape or a definite volume unless enclosed in a container. Defined as electrically neutral medium of positive and negative particles. Plasma is one of the most commonly occurring states of matter in universe. Plasma occurs naturally in the stars. All stars are made of plasma. ○ Because of the presence of plasma stars glow. Plasma is formed because of nuclear fusion in stars. ○ Our sun glows because of presence of plasma. ○ Plasma TV got its name because of presence of plasma in it. ○ Plasma is also found in fluorescent light or neon sign. ○ Plasma is formed when electricity is passed in a fluorescent tube or neon sign, which makes them glow. 3 Bose-Einstein Condensate (BEC) Fifth state of matter. Satyendra Nath Bose and Albert Einstein were predicted about this state of matters, that’s why it got its name as Bose- Einstein Condensate (BEC). Plasma and BEC are has opposite characters. ○ Plasma is a super hot and super excited atom ○ Condensate has super cool and super unexcited atoms. BEC was obtained by cooling the vapour of rubidium-87 at super low temperature by Eric Cornell and Carl Wieman on June 5 1995. After sometimes Wolfgang Ketterle also obtained BEC from sodium-23 at MIT, USA. Cornell, Wieman and Ketterle got Nobel Prize in Physics for this achievement in 2001. Atomic Structure Fundamental Constituents of an Atom An atom contains three basic particles namely protons, neutrons and electrons. The nucleus of the atom contains protons and neutrons. ○ Protons are positively charged. ○ Neutrons are neutral. The electrons are located at the outermost regions called the electron shell. Electron J. J. Thomson, in 1897, discovered negatively charged particles emitted by the cathode towards the anode in a cathode ray experiment. These negatively charged particles are Electrons. Cathode ray experiment J. J. Thomson discovered the existence of electrons. He did this using a cathode ray tube, which is a vacuum-sealed tube with a cathode and anode on one end that created a beam of electrons travelling towards the other end of the tube. The air inside the chamber is subjected to high voltage and electricity flows through the air from the negative electrode to the positive electrode. 4  The characteristics of cathode rays (electrons) do not depend upon the material of electrodes and the nature of the gas present in the cathode ray tube. The experiment showed that the atom was not a simple, indivisible particle and contained at least one subatomic particle – the electron. Protons Ernest Goldstein, in 1886, discovered that with a different condition in the same chamber, anode emitted positively charged particles known as Canal rays or later named as Protons. Neutrons J. Chadwick discovered a subatomic particle with no charge and a mass equivalent to protons in the nucleus of all atoms. These neutrally charged particles are Neutrons. Properties of electrons, protons, and neutrons Property Electrons Protons Neutrons Charge Negatively Charged Positively Charged No Charge Affinity Attracts to positively charged Attracts to negatively Get attracted neither to positive nor charged negative Weight Mass is negligible 1 a.m.u 1 a.m.u Location Outside the nucleus Within the nucleus Inside the nucleus Different Models on Structure of an Atom Thomson’s Model of an Atom J. J. Thomson proposed that the structure of an atom is similar to that of a Christmas pudding where electrons are embedded like currants in the sphere. He proposed that: ○ The structure of an atom is a positively charged sphere that embeds electrons in it ○ An atom is electrically neutral as the protons and electrons are equal in magnitude Drawbacks of Thomson’s Model: ○ Thomson’s structure of an atom failed to explain the arrangement of protons and electrons in its structure. Rutherford’s Model of an Atom Rutherford conducted an experiment bombarding the alpha (α)-particles on a gold foil. He observed the trajectory of the alpha (α)-particles after passing through an atom and drafted some postulates of the experiment, which are: ○ Most of the space in an atom is empty as the particles passed through the gold foil without any hindrance ○ The positively charged centre is called the Nucleus, and all the mass of an atom resides in the centre. The particles deflected 180° after bombarding the nucleus ○ The electrons orbit the centre in a defined path ○ The size of the nucleus is small compared to the total size of the atom Drawbacks of the Model: ○ Although Rutherford presented an entirely new model regarding the structure of the atom, there were a lot of drawbacks which he failed to explain, are- The electrons revolve in an unstable path, and they undergo acceleration radiating energy. 5  When the electrons revolve, they lose energy. Soon electrons would collapse into the nucleus. This tendency would make an atom highly unstable while the atom is highly stable Rutherford’s structure of an atom failed to explain the atomic number concept as it explained only the presence of protons in the nucleus Bohr’s Model of an Atom Bohr devised a model in order to overcome the objections that Rutherford’s model raised. So, he stated the following postulates: ○ An atom permits only a discrete amount of orbitals for the electrons to orbit and make the outer structure of an atom ○ While revolving, the negatively charged particles do not lose energy in these orbitals or energy levels ○ When the electron jumps from one energy shell to another, a change in magnitude takes place Bohr’s model gives an elaborative explanation on the structure of an atom and overcomes the objections faced by all the other models on the structure of an atom. Distribution of Electrons in Distinct Shells Bohr-Bury Scheme suggested the arrangement of particles in different orbits. The following are the rules to write the number of particles in different orbitals: ○ The formula 2n^2 gives the accommodation of the maximum number of electrons in each shell, n=1, 2, 3, 4 for K=2, L=8, M=18, N=32. ○ The outermost orbit can hold a maximum of 8 electrons. ○ The electrons fill the inner levels first as they follow the stepwise filling of orbitals Number of electrons in K-shell: n = 1 ○ 2n^2 = 2 × 1^2 = 2 ○ Maximum number of electrons in K-shell, first shell = 2 Number of electrons in L-shell, n = 2, ○ 2n^2 = 2 × 2^2 = 8 ○ Maximum number of electrons in L-shell, Second shell = 8 Using the formula 2n^2 number of electrons in any shell can be calculated. Valency Valence Electrons - The negatively charged particles present in the outermost shell. ○ These valence electrons are responsible for the valency of an atom. Valency - tendency of an atom to react with the other atoms of the same or various elements. ○ The atoms that fill the outermost paths show chemical activity towards other valence electrons. ○ This reactivity is responsible for the formation of molecules between two or more atoms. The valency becomes zero for an atom when the outer bounds have eight electrons or no electrons to lose. The particle with eight electrons in the outermost shell is an octet, and these molecules are mostly inert in nature. Eg: ○ Magnesium (Mg) has a configuration (2, 8, and 2), so the valency is two. ○ Oxygen (O) (2, 8, and 6) has the valency two as the number electrons it can gain is two to achieve a packed outer energy level. ○ Helium (He) has 2 electrons in its outer shell, Neon (Ne) (2, 8, and 8) has eight electrons in its outer shell. Hence, they do not show any chemical activity. Atomic Number (Z) Atomic number = number of protons present in one atom of an element. As the atom is electrically neutral, the number of protons and electrons are the same. The notation Z denotes an Atomic number. The atomic number of Hydrogen is one as it has only one proton. ○ Number of Protons present in an atom = Atomic number (Z) ○ Number of Electrons present in an atom= Atomic number (Z) ○ Number of Neutrons = Mass number (A)- Atomic number (Z) 6 Mass Number (A) Measure of the total number of protons and neutrons in the nucleus of an atom. The notation A indicates the Mass number. N = total number of neutrons. Mass Number = Atomic Number + Number of Neutrons in the Nucleus ○ A = Z + n° aka Nucleon number. Isotopes The atoms of the same elements with the same atomic number and different mass numbers. Hydrogen has three isotopes: Protium, Deuterium, Tritium. Isobars The atoms of different molecules with the same mass number. Eg, in Calcium, atomic number 20, and argon, atomic number 18, the mass number of both these elements is 40. ○ This shows that the total number of nucleons is the same in the atoms. Metals, Non- metals and Metalloids Metalloids Elements which have the properties of both metals and non-metals are known as metalloids. ○ For example, Boron, Arsenic, etc. 7 Properties of Metalloids They have a metallic luster but behave like non-metals. They are brittle, shiny substances They are solid at ambient temperatures and have relatively high melting points. Melting Temperatures of Metalloids Element Melting Temperature (°C) Boron 2079 Silicon 1410 Germanium 938.3 Arsenic 817 Tellurium 449.5 Antimony 631 They are good electric conductors but poorer than metals. They have intermediate energies of ionisation and values of electronegativity Like non-metals, they form anions, have multiple oxidation states, and form covalent bonds They form metallic alloys. Metalloids and their applications Element Description Application Boron An allotropic semimetal that is extremely hard and heat resistant. Used with silicon to make thermal shock- Has an atomic number of 5. resistant glass. Silicon A grey and shiny semiconductive metal. It has high melting (1,410 Commonly used for semiconductors. °C) and boiling points (3,265 °C). Has an atomic number of 14. Germanium Is hard and brittle in its elemental form. Has an atomic number Less commonly used for semiconductors. of 32. 8 Element Description Application Arsenic A steel-grey semimetal known for being poisonous. It has an Often used as an insecticide. atomic number of 33. Tellurium Brittle in its elemental form. It is a chalcogen, along with selenium Used as a steel additive to improve and sulfur. It has an atomic number of 52. machinability. Antimony A hard and brittle semimetal with an atomic number of 51. Used to colour paints; often alloyed with lead. Metallurgical Principles and methods Metallurgy - a process that is used for the extraction of metals in their pure form. Minerals - The compounds of metals mixed with soil, limestone, sand, and rocks. Metals are commercially extracted from minerals at low cost and minimum effort. ○ These minerals are known as ores. A substance which is added to the charge in the furnace to remove the gangue (impurities) is known as flux. Metallurgy deals with the process of purification of metals and the formation of alloys. Steps in Metallurgical Process The following are the various steps in the metal extraction or metallurgical process: ○ Crushing and grinding the ore. ○ The concentration of ore, is also known as ore enrichment. ○ Metal extraction from concentrated ore. ○ Impure metals are refined or purified. Fig. Copper Flash Smelting Process Principles of Metallurgy The metallurgical process can be classified as the following: ○ Crushing and grinding The first process in metallurgy. Crushing of ores into a fine powder in a crusher or ball mill. This process is known as pulverization. ○ Concentration of ores aka ore dressing. It is the process of removing impurities from ore. In metallurgy, we concentrate the ores mainly by the following methods. ○ Hydrolytic method The ore is poured over a sloping, vibrating corrugated table with grooves. A jet of water is allowed to flow over the surface. 9  The denser ore particles settle in the grooves, and the impurities are washed away by water. ○ Magnetic separation The crushed ore is placed on a conveyor belt. This belt rotates around two wheels in which one of the wheels is magnetic, and therefore the magnetic particles get attracted to the magnetic wheel and fall apart from the non-magnetic particles. ○ Froth floatation The crushed ore is taken in a large tank which contains oil and water. A current of compressed air is passed through it. The ore gets wet by oil and is separated from the impurities in the form of froth. Ore is lighter, and so it comes on the surface and impurities are left behind. ○ Roasting and calcination Roasting - The process of heating a concentrated ore in the presence of oxygen. This process is applied in the case of sulfide ores. ○ Calcination - For ores containing carbonate or hydrated oxides, heating is done in the absence of air to melt the ores. Important ores and alloys Ores A mineral from which a metal can be extracted economically is called an ore. In it, a metal is present in appreciable quantities and from which the metal can be extracted economically. The main active substances present in nature, expecially in the atmosphere are oxygen and carbon dioxide. In the earth's crust, sulphur and silicon are found in large quantities. Sea-water contains large quantities of chloride ions (obtained from dissolved sodium chloride). Most active metals are highly electropositive and therefore exist as ions. It is for this reason that most of the important ores of these metals occur as ○ Oxides ○ Sulphides ○ carbonates ○ halides ○ silicates Some sulphide ores undergo oxidation by air to form sulphates. ○ This explains the occurrence of sulphate ores. Ores are invariably found in nature in contact with rocky materials. ○ These rocky or earthy impurities accompanying the ores are termed as gangue or matrix. Important metals and their ores 10 Alloys Alloys are mixtures of two or more metals and are formed by mixing molten metals thoroughly. ○ In a few cases, non-metals are mixed with metals to produce alloys. Alloying produces a metallic substance with more useful properties than the original pure metals from which it is made. ○ For example, the alloy brass is made from copper and zinc. Properties of alloys Alloys are prepared to impart some desirable properties which the individual metals do not possess. These are, Change in the chemical reactivity: Sodium acts vigorously with water, but Na–Hg amalgam reacts slowly to suit the requirement of some chemical reactions. Hardness: Silver, gold, and soft metals become hard when alloyed with copper. Melting Points: Melting points of an alloy may be higher or lower than any of its components. Wood-metal, which is an alloy of Bi, Pb, Sn and Cd, fuses at 60°C, while none of these metals fuses at this low temperature. Change of colour: Aluminium bronze is an alloy of aluminium and copper. It is of golden, yellow colour and is used in making decoration articles, jewellery and coins while the colour of aluminium is white and that of copper is red. 11  Corrosion resistance: Iron gets corroded soon, whereas stainless Steel, an alloy of iron and chromium, resists corrosion. Casting: An alloy of lead and antimony is known as type metal and is used for casting type required in printing works. Advantages of alloys Alloys do not get corroded or get corroded to a very less extent. They are harder and stronger than pure metals (For example, gold is mixed with copper, and it is harder than pure gold) They have less conductance than pure metals (For example, copper is a good conductor of heat and electricity, whereas brass and bronze are not good conductors) Some alloys have lower melting points than pure metals (For example, solder is an alloy of lead and tin, which has a lower melting point than each of the metals) When metal is alloyed with mercury, it is called amalgam. Important Alloys Alloys of Silver Alloy Percentage composition Uses Coin silver Ag = 90, Cu = 10 For making silver coins. Silver solder Ag = 63, Cu = 30, Zn = 7 For soldering and joining metals Dental alloy Ag = 33, Hg = 52, Sn = 12.5, Cu = 2.0, Zn For filling teeth = 0.5 Silver palladium Ag = 40, Pd = 60 Potentiometers, and winding of some special instruments. Alloys of Iron Name Percentage Uses Stainless steel Fe = 73%, Cr = 18%, Ni = For making utensils, cutlery and ornamental pieces. 8% and carbon Manganese Fe = 86%, Mn = 13% and For Making rock drills, safes etc. steel carbon Tungsten steel Fe = 94%, W = 5% and For making high speed cutting tools. carbon Invar Fe = 64%, Ni = 36% For making watches, meter scales, pendulum rods etc. Nickel steel Fe = 98?96%, Ni = 2?4% For making wire cables, gears, drive shafts etc. Permalloy Fe = 21%, Ni = 78% and For making electromagnets, ocean cables etc. carbon Chrome steel Fe = 98?96%, Cr = 2?4% For making axles, ball bearings and cutting tools such as files. Alnico Fe = 60%, Al =12%, Ni = For making permanent magnents. 20%, Co = 8% 12 Alloys of Copper Alloy Percentage Composition Uses Brass Cu = 80, Zn = 20 For making utensils, condenser tubes, wires parts of machinery etc. Bronze or Cu = 80, Zn = 10, Sn = 10 For making cooking utensils, statues, coins etc. Copper bronze Aluminium Al = 95, Cu = 5 Coins, picture frames, cheap jewellery bronze Gun metal Cu = 90, Sn = 10 For making gun barrels. Bell metal Cu = 90, Sn = 20 For making bells, gongs etc. Constantan Cu = 60, Ni = 40 For electrical apparatus German silver Cu = 60, Zn = 20, Ni = 20 For making silver wire, resistance wires etc. Monel metal Cu = 30, Ni = 67, Fe and Mn = 3 For making acid pumps and acid containers. Phosphor Cu = 95, Sn = 4.8, P = 0.2 For making springs, electrical equipment bronze Gold-copper Au = 90, Cu = 10 For making gold coins, jewellery, watch cases, spectacle rims alloy etc. Alloys of Lead and Tin Alloy Percentage Composition Uses Solder Pb = 50, Sn = 50 For soldering. Pewter Pb = 20, Sn = 80 In making cups, mugs and other utensils. Type metal Pb = 70, Sb = 20 and Sn = 10 For making printing type. Rose metal Pb = 22, Sn = 28, Bi = 50 For making electric fuses. Britannia metals Sn = 90, Sb = 8, Cu = 2 For making table wares. 13 Alloys of Aluminium Alloy Percentage Uses Aluminium bronze Al 95% Coins, utensils, jewellery picture frames etc. Cu 5% Magnalium Al 95% Light instruments, balance beam, pressure cookers etc. Mg 5% Duralumin Al 95% Making aeroplanes, automobile parts pressure cookers Cu 4% etc. Mg 0.5% Mn 0.5% Acids, Bases and Salts Indicators Substances which indicate the acidic or basic nature of the solution by the colour change. Types of Indicator Natural Indicators Indicators obtained from natural sources. Eg: ○ Litmus Obtained from lichens. The solution of litmus is purple in colour. Litmus paper comes in two colours- blue and red. An acid turns blue litmus paper red. A base turns red litmus paper blue. ○ Turmeric: Yellow in colour. Turns reddish brown with base. Des not change colour with acid. ○ Red Cabbage: Juice of red cabbage is originally purple in colour. J Turns reddish with acid and turns greenish with base. 14