knowledge express..............

1. The gas used for inflating balloons is ------ helium.
2. Gas inside an electric bulb is ------ nitrogen.
3. Fertile soils, suitable for growing common crops, is likely to have a pH value of------- 6 to 7.
4. Genetic engineering means ........ modifying the genotype of an organism by in vitro manipulations involving the linking of two DNA molecules.
5. Elements in the Earth Crust Element Weight (%)
O 46.6
Si 27.7
AI 8.1
Fe 5.0
Ca 3.6
Na 2.8
K 2.6
Mg 2.1
Ti 0.44
6. Composition of Air .
Air is a mixture of two major components-N2 and O2
N2 78.1%
O2 20.29%
CO2 0.03%
Water vapour 0.4%
Inert gases 0.95%
7. Heavy water (D2O) is used in nuclear reactors for slowing down the fast moving neutrons, In India, heavy water is produced at Nangal and Narora.
8. The simplest hydrocarbon is -------methane (CH4).
9. Ammonia is used in the manufacture of ice as a refrigerate.
10. pH is defined as the negative logarithm of the reciprocal of the hydrogen ion concentration in gram ion per litre of a solution. pH= - log(1/( H+))
11. A solution with pH of 7 is neutral. The lower the pH of the solution, the more acidic is the compound and the higher the pH of a compound, the greater its basicity.
12. Mercury is the only liquid metal, all others are solids.
13. Calcination is the heating of the ore in the absence of air. This method is employed for obtaining the metal oxides from carbonates and hydroxides.
14. Roasting is the heating of the ore in the presence of air. On ro asting part of the ore is oxidised to form an oxide. This oxide is then reduced to the metal.
15. The industrial reduction process for obtaining metal from the treated ore is called smelting.
16. Natural gas contains 80% methane and, 10% ethane.
17. The quality of petrol for use in car engines is denoted by their anti-knocking properties. The anti-knocking property of petrol samples are measured by the values of their octane number. The highest octane number is 100. To increase octane number, Tetra Ethyl Lead (TEL) is added to petrol.
18. Steel contains 0.25%-2% carbon and varying amounts of other elements.
19. Stainless steel contains 18% chromium and nickel.
20. The extent of pollution of river water is usually measured by oxygen standards. One is dissolved oxygen (DO) which should not be less than 4 mg per litre of water. The other is biological oxygen demand (BoD) and is a measure of organic matter present in water. It should not exceed 3mg per liter of water.
21. Body cells infected with virus produce a protein called interferon.
22. Chocolates can be bad for health because of a high content of Nickle.
23. Mulattos are the offspring of 'pure Negroids and 'pure Caucasoids’.
24. The largest wild life sanctuary in India is Periyar Wild Life Sanctuary.
25. Corbon monoxide- headache, dizziness, decreased physical performance.
# Sulphur dioxide- Aggravation of asthma, Respiratory tract inflammation.
# Nitrogen oxides- Health effects on acute exposure.
# Photochemical oxidants-Respiratory irritation, eye irritation.
26. A vast proportion of our body's weight is made up of water.
27. The industrial applications of fractional distillation are separation of petrol, diesel oil, kerosene oil, heavy oil, etc. from crude petroleum, separation of oxygen, nitrogen, inert gases and CO2 from liquid air, manufacture of spirits such as- whisky, gin, rum and brandy.
28. Acetic acid is pure acid of vinegar obtained by the destructive distillation of wood.
29. Acetylene is used in welding.
30. Adenosine Triphosphate is an intermediate product in photosynthesis.
31. Adrenalin used in the event of Heart-Attack. It leads to increased heart rate, blood pressure and blood sugar.
32. Amphoteric- both acidic and basic-example-Aluminium.
33. Argon-used in electric bulbs and radio tubes.
34. Arsenic-used in making insecticides, glass and medicines.
35. Bakelite-a synthetic resin (plastic) made from phenol and formaldehyde.
36. Bell Metal-Alloy of copper and tin.
37. Benzene-used in motor fuel and dry cleaning.
38. β-rays-high speed electrons (or positrons).
39. Bile-Secretion from the liver, helpful in digestion of food.
40. Blood pressure- In normal human beings, it fluctuates between----- 80 and 120mm of Hg.
41. Blood-sugar-Glucose circulation in blood-its normal level is 90-180 mg per 100 ml of blood in man.
42. Blue vitriol-Crystalline copper sulphate.
43. Chlorine: Used in the manufacture of bleaching powder and for purification of water for civil supplies.
44. Chloroform: Used as a solvent and an anaesthetic.
45. Citric Acid: Occurs in fruits.
46. Dutch oil: An alloy of copper and zinc.
47. Fixed air: Carbon dioxide.
48. Germanium: Used in transistors.
49. Hard water: Salts Ca and Mg.
50. Hydrogen peroxides: Used as bleaching agent and disinfectant.

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