8th chemistry (ENGLISH MEDIUM NEW)

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    Welcome to your 8th chemistry (ENGLISH MEDIUM NEW)

    பெயர்
    மாவட்டம்
    மின்னஞ்சல்
    1.Which of the following is false for gases?

    2. The other name of potassium hydroxide is caustic potash.

    3. The metal which can be cut with a knife.........

    4. The non – metal which is liquid at room temperature is................

    5. The metal which is stored in kerosene..........

    6. Metals are generally good conductors of electricity, but not good conductors of heat.

    7. The property which allows metals to be hammered into their sheets is ........

    8. When carbon dioxide is passed through lime water ............

    9. When a magnesium ribbon is burnt in air, the ash formed is .......

    10. On immersing an iron nail in CuSO4 solution for few minutes, you will observe ..............

    11. Fatty foods become rancid due to the process of ............

    12. Which substance is flushed in bags of potato chips to prevent rancidity?

    13. Corrosion is the natural process by which a naturally pure metal converts into a more stable form of itself like hydroxide or oxide.

    14. Chemical reactions accompanying evolution of heat are called exothermic reactions whereas reactions involving absorbtion of heat are called endothermic reactions.

    15. Tri oxygen molecule is known as ……………

    16. Venus atmosphere consists of roughly 96 – 97% of …………….

    17. Metals like magnesium, iron and sodium bum with oxygen and give basic …………….

    18. Nitrogen is an essential element present in proteins and nucleic acids which are the building blocks of living things.

    19. An average increase in the temperature of the atmosphere is called as acid rain.

    20. Assertion : Carbon dioxide occurs as carbonates in nature. Reason : Carbon dioxide can exist as a liquid at atmospheric pressure.

    21. The process of conversion of iron into its hydrated form of oxide in the presence of air and moisture (humid atmosphere) is called rusting. Rust is hydrated ferric oxide.

    22. The same proportion of carbon and oxygen in the carbon dioxide obtained from different sources proves the law of...................

    23. Which of the following statements made by Dalton has not undergone any change?

    24. find out the wrong pair :

    25. Which of the following scientists observed that cathode rays consists of negatively charged particles?

    26. The equation Na + H2O → NaOH + H2 is ………………

    27. What is the atomic number of an element whose electronic configuration is 2, 8, 1?

    28. When an atom gains an electron it has more number of electrons and thus it carries positive charge.

    29. In the process of electrolysis of water, the positive carbon electrode acts as ……………..

    30. Which one of the following has the highest latent heat of vaporization?

    31. One gram of water requires ……………. of heat to raise its temperature by l°C.

    32. The pleasant taste of drinking water is due to the presence of dissolved substance which include air, CO2 and minerals.

    33. Every litre of sea water contains …………….. grams of dissolved salts.

    34. Amount of heat that is needed to raise the temperature of a unit mass of a substance by 1°C is called ...........

    35. Permanent hardness of water is due to the presence of ………….

    36. Base is a substance that gives ……………. on dissolving in water.

    37. In acidic solution, the colour of the hibiscus indicator paper will change to …………

    38. Acids present in fruits and vegetables are called ……………… acids.

    39. Add few drops of hibiscus indicator in soap solution. What do you observe?

    40. Acidity or indigestion in stomach is due to excessive secretion of ………………

    41. When an acid reacts with a base, neutralisation reaction takes place to give salt and water.

    42. Assertion: To neutralise the excess acid formed in the stomach, milk of magnesia is taken. Reason: Milk of magnesia contains a base called magnesium hydroxide.

    43. Assertion: Methyl orange and phenolphthalein are natural indicators. Reason: Methyl orange is yellow in colour while phenolphthalein is pink.

    44. Which is known as syn gas?

    45. The breaking down of organic matter in an anaerobic condition leads to the formation of ………………….

    46. Which one among the following is an extremely strong but lightweight material is used in mountain bikes and tennis rackets?

    47. Sewage sludge can also be decomposed by microorganisms to produce methane gas along with impurities like carbon dioxide and ……………..

    48. The process of separating petroleum into useful by-products and removal of undesirable impurities is called distillation.

    49. Coke is used in the preparation of dyes, explosives, paints synthetic fibers and pesticides.

    50. ……………. is used as a fuel gas and propellant in aerosol sprays such as deodorants.

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