Science Lc

anandengg's version from 2019-03-21 17:36


Question Answer
Gas most abundant in earth's atmosphere Nitrogen (78%)
Percentage of oxygen in earth's atmosphere 21% (appx)
The lightest gas Hydrogen
The heaviest gas Radon
Tear Gas Ammonia (NH3)
Marsh gas Methane
Laughing gas Nitrous Oxide (N2O)
Natural gas Mainly methane with small quantities of ethane and propane
Gobar gas Methane, CO2 and hydrogen
Gas with foul smell Hydrogen Sulphide (H2S)
Gas mixed with oxygen and given to patients with restricted breathing Helium
A major air pollutant, the percentage presence of which is checked in vehicle pollution test Carbon monoxide
The gas which is responsible for the formation of brown air in traffic congested cities Nitrogen Dioxide
Major gaseous pollutant of areas located near thermal power station Suphur dioxide
Strong smelling substance added to LPG Ethyl Mercaptan or Ethanethiol
Gases responsible for depletion of ozone layer Chloroflouro carbons
Gas responsible for acid rain Sulphur dioxide
Gas used in gas welding and also artificial ripening of fruits Acetylene
Gas used in electric bulbs Argon
Gas used in flourescent lamps Mercury vapour
Gas used in LPG Butane, Propane and Ethane
Gas used in refrigeration Freon (Diflouro Dichloro Methane)
Gas used as an anaesthetic in dental surgery Nitrous Oxide
he Periodic Table was created by Dmitry Mendeleyev, a Russian chemist and professor in 1869.
The Periodic Table has 7 rows or periods.
The present Periodic Table has room only for 118 elements.
Lanthanides is a group of 15 elements from atomic number 57 to 71. Together with Scandium and Yttrium they are known as rare earth elements.
Rare earth elements which are 17 in number are actally not rare. Most of them are commonly found
Actinides is a group of 15 elements from atomic number 89 to 103. All actinides are radioactive.
The Periodic Table has 18 columns or groups. Some important groups are listed below.
Group 1 - Alkali metals or Lithium group consists of Lithium, Sodium, Potassium, Rubidium, Cesium and Francium.
Group 2 - Alkaline earth metals or Beryllium group consists of Beryllium, Magnesium, Calcium, Strontium, Barium and Radium.
Group 15 - Pnictogens or Nitrogen group consists of Nitrogen, Phosphorus, Arsenic, Antimony, Bismuth and Moscovium.
Group 16 - Chalcogens or Oxygen group consists of Oxygen, Sulphur, Selenium, Tellurium, Polonium and Livermorium.
Group 17 - Halogens or Flourine group consists of Flourine, Chlorine, Bromine, Iodine, Astatine and Tennessine.
Group 18 - Noble gases or Helium or Neon group consists of Helium, Neon, Argon, Krypton, Xenon, Radon and Oganesson.

Atoms of elements can have different number of electrons and neutrons.

Question Answer
A variant of an element with different number of neutrons is known as its Isotope
Different physical form of an element is known as its (e.g. graphite and diamond) Allotrope
Element most abundant in the Universe Hydrogen
Element most abundant in the human body Oxygen
Element which forms more than 10 million compounds Carbon
Element with the lowest melting and boiling point Helium
Element with the highest melting point Carbon
Element with the highest boiling point Tungsten
Element with highest density Osmium
Element with lowest density Hydrogen
Element with highest electronegativity Flourine
Element with lowest electronegativity (highest electropositivity) Francium
The first element to be produced artificially Technitium
The most corrosion resistant element (which cannot be affected by water, chemicals or acids) Iridium
The element which was discovered on the Sun before it was found on the Earth Helium
The non-metallic element which is liquid at room temperature Bromine
The metallic element which is liquid at room temperature Mercury
The most reactive element Flourine
Fact to remember Name of the metal
Question Answer
The metal with the highest melting point Tungsten
The metal with the highest thermal conductivity Silver
The metal with the highest electrical conductivity Silver
The metal with the highest density Osmium
The metal with the lowest density Lithium
The most malleable and ductile metal Gold
The least reactive metal Platinum
Metal most abundant in earth’s crust Aluminium
Metal which forms amalgam with other elements Mercury
Metal used in a fuse wire and also in solder Lead-tin alloy
Metal used in the filament of a bulb Tungsten
Metal which pollutes the air of cities having large number of vehicles Lead (reason for using unleaded petrol)
Metal used in the filaments of electric heaters Nichrome
Metal used as radiation shield Lead
Metal into which Uranium turns when it loses all its radioactivity Lead
Metal used for making boats because it does not corrode by seawater Titanium
Alloy Combination of
Question Answer
Duralumin Aluminium and Copper
Brass Copper and Zinc
Bronze Copper and Tin
Invar Iron and Nickel
Stainless steel Iron, Chromium and Nickel
German Silver Copper, Nickel and Zinc
Gunmetal Copper, Tin and Zinc
Solder Lead and Tin
Electrum Gold and Silver
Constantan Copper and Nickel
Manganin Copper, Manganese and Nickel
Manganin is a trademarked name.
Ores of Metals
Question Answer
Metal Ore
Aluminium Bauxite
Beryllium Beryl
Chromium Chromite
Cobalt Cobaltite
Copper Bornite, Chalcocite
Gold Quartz
Iron Magnetite
Lead Galena
Manganese Pyrolusite
Mercury Cinnabar
Nickel Pentlandite
Tin Casseterite
Tungsten Wolframite, Scheelite
Silver Argentite
Uranium Uraninite
Zinc Sphalerite
Base Units
Physical Quantity Unit of Measurement
Question Answer
Length Metre
Mass Kilogram
Time Second
Electric Current Ampere
Thermodynamic Temperature Kelvin
Amount of Substance Mole
Luminous Intensity Candela


Derived Units
Physical Quantity Unit of Measurement
Question Answer
Angle Radian
Frequency Hertz
Force Newton
Weight Newton
Pressure Pascal
Energy Joule
Work Joule
Heat Joule
Power Watt
Electric Charge Coulomb
Potential Difference Volt
Electromotive Force Volt
Electric Resistance Ohm
Electric Capacitance Farad
Electric Conductance Siemens
Inductance Henry
Magnetic Flux Weber
Magnetic Flux Density Tesla
Radioactivity Becquerel
Units of Length
Question Answer
1 inch = 2.54 centimetres
1 cm = 0.3938 inches
1 yard = 0.9144 metres
1 metre = 1.093 yards
1 mile = 1.609 km
1 kilometre = 0.6213 miles
1 nautical mile = 1.852 kilometres
1 kilometre = 0.5399 nautical miles
1 fathom (6 feet) = 1.828 metres
1 metre = 0.5468 fathoms
1 mile = 5280 feet
1 nautical mile = 6076.16 feet


Units of Weight
Question Answer
1 ounce = 28.349 grams
1 gram = 0.03527 ounces
1 pound = 453.592 grams
1 kilogram = 2.204 pounds
1 bale (cotton in India) = 170 kilograms


Units of Volume
Question Answer
1 gallon = 3.785 litres
1 litre = 0.264 gallons
1 litre = 1000 cubic centimetres
Question Answer
1 cc = 0.001 litre
1 litre = 2.1134 pints
1 pint = 0.4731 litre
1 barrel (oil) = 158.99 litres
Question Answer
1 barrel = 42 US gallons


Units of Area
Question Answer
1 acre = 4046.85 square metres
1 square metre = 0.000247 acres
1 hectare = 10,000 square metres
1 square metre = 0.0001 hectare


Units of Quantity
Question Answer
1 quire = 25 sheets
1 ream = 500 sheets
1 bundle = 1,000 sheets
1 bale = 5,000 sheets
1 dozen = 12 units
1 gross = 12 dozen


Instrument Use
Question Answer
Bolometer Instrument for measuring radiation by means of the rise in temperature.
Hydrometer Instrument for measuring the density of liquids.
Hygrometer Instrument for measuring the humidity of the air or a gas
Lactometer Instrument for measuring the amount of water in milk
Anemometer Instrument for measuring wind force.
Salinometer Instrument for measuring the salinity of a solution
Altimeter Instrument for measuring the altitude of an aircraft etc.
Galvanometer Instrument for detecting and measuring electric currents


Question Answer
Telescope Optical instrument using lenses or mirrors to magnify distant objects.
Microscope Instrument with lenses for magnifying objects or details invisible to the naked eye.
Stethoscope Instrument used in listening to the heart, lungs, etc. [Greek stethos breast]
Kaleidoscope Tube containing mirrors and pieces of coloured glass etc. producing changing reflected patterns when shaken.
Endoscope Instrument used to examine the interior of a hollow organ or cavity of the body
Oscilloscope Device for viewing oscillations by a display on the screen of a cathode-ray tube.


Question Answer
Crescograph Instrument for measuring growth in plants
Seismograph Instrument that records the force, direction, etc., of earthquakes.
Cardiograph Instrument recording heart movements.
Heliograph Signalling apparatus reflecting sunlight in flashes.
Radiograph Instrument recording the intensity of radiation

Facts to Remember

Question Answer
The speed of sound is 343 m/s
The audible range of sound in human beings is 20 Hz to 20,000 Hz
The level of sound prolonged exposure beyond which may cause permanent hearing loss 85 dB
A woman’s voice is shriller than a man’s voice because of higher Pitch
The animals which produce sounds of high pitch and frequency to communicate and locate each other Dolphins and elephants
The loudness of sound is measured in Decibels
Stringed instruments have boxes attached to increase the Loudness of the sound produced
The minimum distance which is required to hear an echo 17 metres
The system of sound reflection used to find the depth of oceans SONAR (Sound navigation ranging)
The phenomenon which makes the sound of an approaching train shriller Doppler effect
Sounds cannot travel in vacuum
Sounds travel faster in metals than in air
Sonic boom occurs when a super sonic aircraft crosses the sound barrier
Light Waves Sound Waves
Light waves do not require a medium to travel. Sound waves require a medium to travel.
The speed of light waves is 3 x 108 metres per second Sound waves travel at a speed of 332 m/sec
Light waves are electromagnetic waves.
Sound waves are mechanical waves.
Variation in frequency of wave gives different colours.
Variation in frequency of sound waves gives sound with different pitch.
Light waves can travel very long distances
Sound waves cannot travel long distances as their energy is dissipated easily.

Images formed by Concave Mirror

Question Answer Column 3
Position of object Position of image Nature of image
At infinity At focus (F) Real, diminished, inverted
Beyond centre of curvature (C) Between F and C Real, diminished and inverted
At C At C Real, same size, inverted
Between C and F Beyond C Real, enlarged, inverted
At F At infinity Real, enlarged, inverted
Between F and P Behind the mirror Virtual, enlarged and upright
Irrespective of the position Behind the mirror Virtual, diminished, upright

Sodium Compounds

Common Name Chemical Name Formula
Question Answer
Washing soda Sodium carbonate Na2CO3
Baking soda Sodium bicarbonate NaHCO3
Borax Sodium tetraborate decahydrate Na2B4O7·10H2O
Brine Aqueous sodium chloride solution NaCl
Caustic soda Sodium hydroxide NaOH
Hypo Sodium thiosulfate Na2S2O3


Calcium Compounds
Common Name Chemical Name Formula
Question Answer
Bleaching powder Calcium hypochlorite Ca(ClO)2
Quick Lime Calcium oxide CaO
Marble Calcium carbonate CaCO3
Plaster of paris Calcium sulfate CaSO4
Chalk Calcium carbonate CaCO3
Gypsum natural Calcium sulfate CaSO4·2H2O


Other Compounds
Common Name Chemical Name Formula
Question Answer
Alum Aluminium potassium sulfate KAl(SO4)2.12H2O
Aqua regia Nitrohydrochloric acid HNO3 + 3 HCl
Aspirin Acetylsalicylic acid C9H8O4
Corundum (ruby, sapphire) Aluminium oxide Al2O3
Dry ice Solid Carbondioxide CO2
Epsom salts Magnesium sulfate MgSO4·7H2O
Heavy Water Deutrium oxide 2H2O or D2O
Pearl Ash Potassium carbonate K2CO3
Plumbago Graphite C
Prussic acid Hydrogen cyanide HCN
Jeweller's rouge Ferric oxide Fe2O3
Saltpeter Potassium nitrate KNO3
Table sugar Sucrose C12H22O11
Talc or talcum Magnesium silicate Mg3Si4O10(OH)2
Vinegar Acetic acid CH3CO2H


Use Chemical
Question Answer
Chemical with which flourescent lamps are coated for providing illumination Phosphor
Chemical used to remove rust stains from clothes Oxalic acid
Chemical with which photographic films are coated Silver Bromide
Chemical in which gold dissolves Aqua Regia
Chemical with which non-stick cookware is coated Teflon
Chemical used in the manufacture of matches Phosphorus
Chemical used to purify water (as a disinfectant) Chlorine
Chemical used as an antiseptic in mouth freshner, toothpastes etc. Hydrogen Peroxide
Chemicals used in the breath test to check drunken driving Potassium dichromate and Sulphuric acid
Chemical used as a purgative Magnesium Sulphide
Chemical used in cloud seeding Silver Iodide
Chemical used as a fixing agent in photography and also for washing as a germicide Sodium thiosulphate
Chemical commonly used in explosive devices as well as fertilisers Ammonium Nitrate
The substance which is used to make capsule shells in pharmaceutical industry. The substance is also used as gelling agent in cooking. Gelatin
The sugarcane industry product being blended with petrol to reduce pollution and also to reduce the import burden of petrol in India Ethanol
The organic compound widely used as a cleaning agent in dry cleaning Tetrachloroethylene (perchloroethylene)
The chemical commonly used in baby diapers for its super absorbent properties Sodium polyacrylate
The chemical used for embalming bodies and preservation of animal specimens and tissue samples Formalin (aqeous solution of formaldehyde)
The compound which is used in moisturing creams and soaps because of its hygroscopic properties Glycerol
The chemicals used to produce fog/smoke on theatrical stages or studios 1. Dry ice 2. Glycol and water mix
The chemical used as anticoagulant in blood collection tubes and for the preservation of blood in blood banks Sodium Citrate
The chemical commonly used as rodenticide Zinc Phosphide
The chemical commonly used in sunscreen lotions, cigarette filters, ceramic industry Zinc Oxide

Name Chiefly found in Formula

Question Answer
Lactic acid Sour milk C2H4OHCOOH
Acetic acid Vinegar CH3COOH
Formic acid (Methanoic acid) Ant venom HCO2H
Citric acid Citrus fruits like lemon, lime, orange C6H8O7
Oxalic acid Rhubarb, spinach H2C2O4
Butyric acid Milk, butter CH3CH2CH2-COOH
Lauric acid Coconut oil CH3(CH2)10COOH
Malic acid Sour apples, sour grapes HO2CCH2CHOHCO2H
Tartaric acid Grapes, tamarinds, pineapples C4H6O6
Erucic acid Rapeseed oil, Mustard oil CH3(CH2)7CH=CH(CH2)11COOH