- Modern astronomy was founded by Ni cholas Copernicus, a Polish astronomer (1473 A.D. to 1543 A.D.).
- AU (Astronomical Unit) represents the mean distance between the Sun and the earth.
- 1 AU = 149,600,000 km. (or 93 million miles).
- 1 Light year = 60,000 AUs
- Galaxies are giant clusters of stars, gases and dust.
- Of the 1000 brightest galaxies about 75% are spiral, 20% elliptical and 5% irregular.
- Elliptical galaxies have stars predominantly old.
- Spiral galaxies have bright young stars.
- SO galaxies (Irregular galaxies) have old stars.
- The nearest galaxy to our own (the milky way, a spiral galaxy) is the magellan (about 100,000 light years distant from us). Another is Andromeda.
- The Sun takes about 24 million years to complete one revolution around the galactic nucleus which is called the galactic year.
- Red Giants are stars which have consumed at least 10% of their hydrogen (the fuel) on account of which they appear reddish.
- After exhaustion of its fuel a star contract in the core region but expand in outer sphere. This stage of star is called giant or supergiant.
- The giant stage of our Sun will be after 500 billion years.
- Expansion of giant star leads to its explosion, known as a nova or, supernova.
- Supernova explosion leads to a dwarf star if the original mass of the star was less than about 2 solar masses.
- Explosion leads to the Neutron stars if the original star mass was between 2 to 5 solar masses.
- Neutron stars have very large magnetic fields and emit pulses at regular intervals, known as pulsars.
- If the original solar mass was more than 5 solar masses, its explosion forms Black Hole.
- Black hole has large gravitational field and any thing even photons within its reach would be engulfed by it.
- Nebulae are the clouds of rarefied gas existing between stars and glow due to the radiation of stars.
- The nearest star after Sun is Alpha Centauri, some 4 * 1014 kms. away from the earth.
- The Sun spots, the dark spots on the Sun, appears dark because of lower temperature of about 4500 K.
- Sun spots has intense magnetic fields.
- The number of Sun spots vary from year to year with a period of about 11 years. This periodicity is known as Sun spot cycle.
- Solar flare is the sudden increase of the intensity in solar radiation.
- During a flare, the Sun emits streams of protons, electrons and alpha particles which reach the earth about a day later causing global magnetic storms and radio disturbances.
- From 1979-1999, Neptune is the farthest planet, after then Pluto will be the farthest for 228 years.
- After moon, Venus is the brightest object in the night sky. It is called ‘morning’ and evening star.
- Except Venus and Mercury all the other planets have satellites.
- Uranus has 15 moons and Neptune 8.
- Important moons are IO of Jupiter, Titan of Saturn, Colourful Triton of Neptune and Charon of Pluto.
- A geostationary orbit has an altitude of 35,784 km.
- Escape velocity from earth, 11.2 km/second; from moon, 2.4 km./second ; from the Sun, 617.7 km/second.
- Halley’s Comet moves around the Sun in 76 year. Its first appearance was in 466 B.C. and the latest in 1986.
- Rings of Saturn were first seen by Galileo.
- Early Bird was world’s first communication satellite launched by the USA.
- ‘Apollo 13’ moon landing mission of USA failed to reach the moon and had to return to the earth with the crew safe and sound.
- The mass of the moon is 1/81 of the mass of earth.
- Orbiter was the first space shuttle of USA and the world.
- 12 Americans visited the moon in Apollo-11 mission.
(i) gain of oxygen or other electronegative element; or,
(ii) loss of hydrogen or, other electropositive element; or,
(iii) increase in valency of metal; or,
(iv) loss of electron
(i) gain of hydrogen or, other electropositive elemer; or,
(ii) loss of oxygen or other electronegative element; or,
(iii) decrease in valency of a metal ; or,
(iv) gain of electron.
- Oxidizing agents are those which oxidize other substances and themselves get reduced.
- Reducing agents reduce other substances and themselves get oxidized.
- A reaction in which heat is liberated is termed as Exothermic Reaction.
- A reaction in which heat is absorbed from surroundings is termed as Endothermic Reaction.
- Dialysis is the process of separating colloidal particles from crystalloids by enclosing in a parchment membrane placed in running water.
- In Primary Batteries (Dry cells), not rechargeable, anode (zinc) is the negative plate and the cathode (graphite) is the positive plate, with ammonium chloride as electrolytes.
- In secondary or, storage Batteries, rechargeable, lead sponge is the negative plate (anode), lead oxide is the positive plate (cathode), with sulphuric acid as electrolytes.
- Electroplating is the electro deposition of metals on metals, alloys and non-metals.
- In Electrolysis, compounds are broken down electrically.
- Hydrogen liquefies at a temperature of -252°C.
- Uses of hydrogen in filling balloons and gas bags for air ships. in producing oxy-hydrogen flames used for cutting and welding metals. and for the preparation of vanaspati ghee.
- Alkaline pyrogallol solution turns brown as oxygen dissolves in it.
- Ozone is an allotropic form of oxygen, formed in air from lightning.
- A sample of water, in which when soap is added do not form lather, is called hard water. It contains soluble salts of calcium & magnesium or iron.
- Temoporary hardness, which is due to the presence of bicarbonates of calcium and magnesium, can be removed by boiling.
- Permament hardness of water is due to the presence of sulphates, chlorides, nitrates, etc. of calcium, magnesium and other metals.
- Permanent hardness can be removed by boiling, Clark’s method (by addition of milk lime), adding washing soda or by Permutit process.
- The halogen family consists of the elements of flourine, chlorine, bromine, iodine and astatine.
- Allotropic forms of sulphur are
(i) Rhombic, Octahedral or a-sulphur;
(ii) Monoclinic, prismatic or b-sulphur; and
(iii) Plastic sulphur or g (gamma) sulphur.
- Allotropy can be defined as the existence of an element in more than one form in the same physical state.
- Diamond is the purest and hardest carbon. It is transparent to light and X-rays and possess high refractive index.
- Diamond is a bad conductor of heat and electricity.
- Graphite is a good conductor of heat and electricity.
(i) lubrication of electric motor ;
(ii) atomic energy,
(iii) manufacture of lead pencils;and (iv) making shoe polish and paints.
(i) Anthracite is the best variety of coal which burns without any smoky flame. Carbon content 90%.
(ii) Bitumirous has 80% carbon and is hard. Burns with smoky flames.
(iii) Lignite contains around 70% carbon.
(iv) Peat have around 70% carbon.
- Cold drinks contain some carbonic acid which gives them a tingling taste.
- Acids have no effect on phenolphthalein solution but turn blue litmus red, and methyl orange red.
- Bases have no effect on blue litmus but turn red litmus blue, methyl orange yellow and phenolphthalein pink.
- Nitrogen and oxygen are present in the ratio 4:1 in air and 2:1 in air dissolved in water.
- At high pressure and low temperature, air can be liquefied.
- When liquid air is allowed to evaporate, nitrogen vapourises first (B.P. 196°C) leaving behind liquid oxygen (B.P. 183°C)
- Portland cement is made of lime, alumina, silica and iron oxide. Small amounts of magnesia, sodium, potassium and sulphur are also present.
- Glass used for preperation of bulbs is called flint glass, because it contains lead silicates.
- Ordinary glass is called soda lime glass. It has lowest electrical conductivity and high structural and tensile strength.
- Raw materials used in glass manufacture are sodium carbonate, lime, etc. Special additional material for preparation of crook’s glass is cerium oxide (CeO).
- Cerium oxide is a white crystalline powder and is used in polishing glass.
- Pyrex glass is heat resistant.
- Liquid oxygen boils at 183°C.
- Ozone is more soluble in water than oxygen, because ozone is more effective oxidizing agent than oxygen.
- Galvanized iron is coated with zinc because zinc coating helps in preventing any corrosive effect.
- Naturally occurring uranium disintegrates to form stable isotopes of lead.
- Atomic hydrogen has a half life of fraction of a second.
- Heavy water is obtained by prolonged electrolysis of water.
- Like ordinary water, heavy water dissolves salts. Solubility of sodium chloride in heavy water is less than thatof ordinary water.
- Fats used in soap making are esters of glycerine and stearic, oleic and palmitic acid.
- Synthetic detergents are sodium salts of fatty acids.
- Detergents produce lather in soft as well as in hard water.
- 95% ethanol is known as rectified spirit.
- Gasonol is a combination of gasolene and alcohol.
- Marsh gas, which is formed from decaying organic matter in the coal mines, is the common name for methane.
- Gay Lussac’s Law is valid for those gases which on mixing react with each other.
- Gay Lussac’s Law states that at constant pressure, the volume of confined gas is proportional to its absolute temperature. The volume of gases involved in a chemical change can always be represented by the ratio of small to whole number.
- Gay Lussac’s Law of gaseous volumes is derived from Dalton’s Law.
- Law of multiple proportion was enunciated by Richter.
- Fertilizer called nitro chalk isa mixture of chalk and potassium nitrate.
- Crystals of some substances, when exposed to dry air, lose their crystalline shape. This property is called efflorescence. Example—Glauber's salt and washing soda.
- Substances like quicklime, sulphuric acid absorb moisture from air and are called hygroscopic.
- If the absorption is such that the substance is dissolved in it, then this property is called deliquescent. Examples—chlorides of magnesium and calcium and hydroxides of sodium and potassium.
- Common salt gets wet in rainy season, not because it is deliquescent but because it contains traces of magnesium chloride which is highly deliquescent.
- Human hair is hygroscopic.
- Copper, Silver and Gold are the three coinage metals placed in IB group of the Periodic Table.
- In the preparation of sensitive plates or films, colloidal AgBr or AgI in gelatin is used. It is sensitive to light.
- Hypo is the solution of sodium thiosulphite (Na2S2O3).
- In silvering of mirror, ammonical silver nitrate is heated with aldehyde (glucose solution) in this process.
- Microcosmic salt is Na (NH4). HPO4 .4H2O.
|Colour of glass||Adding compound|
Cadmium, Silver or Sulphur
Gold and Tin or, Selenium and Cadmium
- Palaeontology is the study of fossils.
- Cryptogams never bear flowers or seeds, hence, commonly known as “Flowerless” or “Seedless” plants.
- Phanerogames are the higher, advanced plants which always bear flowers and seeds, hence, known as “flowering” or “seed bearing” plants.
- Algae are green plants having chlorophyll but no root, stem, or leaves.
- Fungi are non-green plants lacking chlorophyll and have no root, stem, or leav es. Plant body is my celi um which is made of thread like hyphae.
- Bryophyta are higher green cryptogams. Examples Riccia, Marchantia, Moss. etc.
- Pteridophyta are the highest cryptogams have true root, stem and leaves.
- Among cryptogams, xylem and phloem first appear in Pteridophyta.
- Gymnosperms are the lower flowering plants. They have no fruits hence seeds are naked. Examples—Cycas, Pinus, Gnetum.
- Angiosperms are the higher flowering plants. Seeds are enclosed in well developed fruits. Examples—Gram, Pea, Mango, etc.
- Cell wall is the non-living, outermost covering of cell and is made up of cellulose.
- Cell wall is present in all plant cells but is lacking in animal cells.
- Plasma membrane is universally present in all type of cells. It is living, made of protein and lipids, and located beneath the cell-wall.
- In the cytoplasm, living organelles like mitochondria, plastids (in plant cell), golgi bodies, endosplasmic reticulum, ribosomes, nucleus, etc. are present.
- Mitochondria is called the Power House of cell, because it produces “energy currency” in the form of ATP (Adenosine Tri-Phosphate).
- Nucleus, the ‘control centre’ of the cell, are made up of 2 kinds of nucleic acids—DNA and RNA.
- As a result of mitosis (cell division), two daughter cells are formed, both having an identical component of chromosomes and hence of genes.
- The four phases of mitosis are—
(i) Prophase, (ii) Metaphase, (iii) Anaphase, and (iv) Telophase.
- In flower, the four floral whorls and their units are—
- Transpiration is the evaporation of water by the aerial parts of plants, under the influence of sunlight.
- Transpiration occurs through stomata as well as cuticle.
- Rate of transpiration is measured by Ganong’s Potometer. qImportance of transpiration—
(i) elimination of excess water absorbed;
(ii) increases absorption of water;
(iii) regulation of temperature;
(iv) distribution of salts and water.
- Photosynthesis is the building up of carbohydrates in presence of light by the green parts of the plant.
- Photosynthesis occurs in chloroplasts.
- Photosynthesis has two phases— (i) Light phase: Light sensitive; and liberation of oxygen from water. (ii) Dark phase: Temperature sensitive; and synthesis of carbohydrates.
- Reaction of Photosynthesis:
6CO2 + 6H2O → C6H12O6 + 6O2
- Autotrophic plants can make food by their own.
- Heterotrophic plants cannot make food by their own; hence, are dependent on others. Heterotrophic plants are— Parasites: Cuscuta, Sandal wood, Rafflesia, etc. Saprophytes: All fungi, Bacteria, etc. Carnivorous: Pitcher plant, Sundew, Bladderwort, etc. (catch insects for nitrogen food) Symbionts: Lichen, Rhizobium bacteria, Blue-green algae, etc.
- Respiration is the catabolic process which oxidises food to release energy and carbon dioxide.
- Reaction of respiration is
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
- Fermentation is the type of respiration, due to activity of micro-organism, like yeast by enzymatic action of zymase.
- Hormones are the organic substances which influence the growth or physiological activities of plants. The naturally occuring plant hormones are Auxin, Gibberellins, Cytokinins, Abscisic acid and Ethylene.
- Vernalisation is the method of inducing plants to flower early. It is the pre-treatment of seeds with certain temperature difference.
- Practical benefits of vernalisation are to induce flowering and early maturing of the crop, to escape drought, flood and frost.
- Photoperiodism is the time of flowering to the daylength of the period of illumination. In photoperiodism, treatment is of plant parts but not of seeds as in vernalisation.
- Artificial shortening or lengthening of day-length by electric illumination has induced plants to flower earlier than the normal plants.
- Viruses outside the host are non-living substance while once inside the host they function as a living body.
- Since, viruses possess both living and non-living features, they are supposed to be the connecting link between living & non-living.
- Cells which lack nuclear membrane and organelles like mitochondria, chloroplast, endoplasmic reticulum, golgi body, etc. are known as Prokaryotic cell. While those cells in which all the above structures are present are called Eukaryotic cell.
- Protein Synthetic machinery in a cell includes mRNA, tRNA and ribosomes containing rRNA.
- Mitosis occurs in somatic cells whereas meiosis in reproductive cells.
- As a result of meiosis 4 daughter cells are formed, each having half the chromosome number of parents.
- Lichens, symbiotic plants, play an important part with mosses in primary colonisation of bare areas.
- The food material stored in the onion, garlic, ole, potatoes, sweet potatoes is in the underground stem
- The food material stored in the radish, turnip, carrot, is stored in the roots.
- The technique of growing plants in liquid medium or, nutrient solution is termed as hydroponics.
- Two branches of plant can give two different fruits: tomatoes and brinjals. This is acheived by grafting.
- One cup of coffee contains about 150 mg. of caffein.
- Plasmodium (malerial parasite) reproduces sexually in mosquito whereas asexually in man.
- Cold blooded animals are those animals whose body temperature changes with the temperature of the atmosphere, for example, fishes, reptiles, etc.
- Warm blooded animals maintain a constant body temperature, independent to that of usual surroundings. For example— birds, mammals, etc.
- Parental care in birds is quite like mammals. Fishes, amphibians and reptiles have not so well developed parental care.
- The condition of occurring two kinds of teeth (in man) milk teeth and permament teeth—is called diphyodont.
- When the teeth are present inside the sockets, it is known as thecodont.
- The eyes of cat, cow and buffaloes shine at night because tapetum lucidum is present outside the retina.
- Dr. Har Govind Khorana was awarded Nobel Prize for doing research on genetic code.
- Nervous system is affected by shortage of sodium, because sodium takes part in transferring of nerve impulses in our body.
- Mineral accounts for 4% of our body weight.
- Standard requirement of protein for a normal adult is about 50 gram per day.
- A labourer doing heavy work requires about 4,500 calories per day.
- The largest gland found in human body is liver.
- 100 ml. of blood carries 15-20 ml. of oxygen.
- Normal human adult male has 14 gm. of haemoglobin per 100 gm. of blood.
- Human heart transplant operation was first performed by Christian Bernard, a South African doctor.
- In case of snake bite, a piece of cloth is tightly tied above the bite to prevent the blood from returning to heart.
- During snake bite the RBCs are destroyed by the process termed as haemolysis.
- When Rh positive male marries Rh negative female, the result would be fatal.
Rh-negative individuals do not normally possess antibodies against the antigen. But they can acquire such antibodies by blood transfusion or in the case of a woman by bearing Rh-positive children, whose antigen crosses the placenta. The antibody thus formed in a Rh-negative mother may damage the Rh-positive foetus.
In the above condition, first issue of the woman would be normal because till then the sufficient antibodies to kill the foetus is lacking.
- Blood circulation was discovered by William Harvey.
- Antigen is the foreign particle, like micro-organism, which when comes in human blood stream induces the WBC to form antibody.