Chemistry

Q.  Why does a liquid remain hot or cold for a long time inside a thermos flask? A.  The presence of air, a poor conductor of heat, between the double glass wall of a thermos flask, keeps the liquid hot or cold inside a flask for a long time. Q.  Why is it recommended to add salt to water while boiling dal? A.  By addition of salt, the boiled point of water gets raised which helps in cooking the dal sooner. Q.  Why do some liquid burn while others do not? A.  A liquid burns if its molecules can combine with oxygen in the air with the production of heat. Hence, oil burns but water does not. Q.  What chemical is represented by the symbol Sn? A.  Tin Q.  During digestion Proteins are broken into what? A.  Amino Acids Q.  Which alloy is used for making air-crafts? A.  Duralumin Q.  How harmful is caffeine? A.  Caffeine is a type of chemical, known as an alkaloid, which occurs in several kinds of plant. Biologists do not fully understand why plants such as coffee and tea make caffeine, but one theory is that it has evolved as a natural herbicide to help growing shrubs overcome competing plants. The effects of caffeine vary. Women retain caffeine in their body for much longer when they are pregnant, where as smokers eliminate caffeine twice as quickly as non-smokers. The most noticeable effect is to stimulate the nervous system; people whop are sensitive to caffeine will certainly sleepless if they drink ordinary coffee before going to bed. However, the body can become habituated to caffeine and many regular coffee drinkers can take a cup or two in the evening without their sleep being disturbed. Other physiological effects of caffeine include stimulating the production of urine and susceptible to irregular heart rhythms and palpitation find that these are triggered by caffeine. Caffeine dose not accumulate in the body, so its effects are short-lived. But it has been accused at one time or another of contributing to most of the serious health problems of the 20th century, including heart disease, cancer and birth defects. Q.  Presence of bicarbonates of Calcium and Magnesium in water leads to A.  Temporary hardness of water Q.  Stainless steel contains A.  Ans : Iron, Chromium and Nickel Q.  White phosphorus is stored under A.  Water Q.  Which gas comes in third position in volume in atmosphere after Nitrogen & Oxygen? A.  Argon Q.  Amalgam is an alloy in which one of the compound is A.  Mercury Q.  Atomic number is equal to A.  Number of protons Q.  Which is the anti-knocking compound used in petrol in order to enhance the capacity of petrol engine? A.  Tetra Ethyl Lead Q.  "Aqua Regia" is a mixture of A.  Hydrochloric acid and Nitric acid Q.  The chief chemical component of pearl is A.  Calcium carbonate Q.  Global warming is due to increased production of all the following, except A.  Carbon dioxide Q.  Which acid is present in lemon A.  Citric acid Q.  Brass is an alloy of copper and A.  Zinc Q.  The hardest natural substance known in the world is A.  Diamond Q.  Permanent hardness of water may be removed by the addition of A.  Sodium carbonate Q.  Which is Vinegar? A.  Acetic acid Q.  Which of the following gas is used in cigarette lighters? A.  Butane Q.  Baking Soda is also known as A.  Sodium bicarbonate Q.  Bond order of a molecule can be at the maximum of A.  3 Q.  Neutral molecules in which one of the carbon atoms has six valence electrons are called A.  Carbenes Q.  Which of the following is non-radioactive? A.  Deuterium Q.  Which of the following is a thermo setting plastic? A.  PVC Q.  By which process, Octane number of petroleum can be increased? A.  Atomization Q.  Atoms of the same element having the same atomic numbers but different atomic weights are called A.  Isotopes Q.  What is the main constituent of soap? A.  Sodium hydroxide Q.  Name a fertilizer that contain maximum amount of Nitrogen A.  Urea Q.  Which compound is called oil of wintergreen? A.  Methyl Salicylate Q.  What is alum? A.  Potassium Aluminium Silicate Q.  A minute amount of radio isotope is called A.  Tracer Q.  Name an alloy of copper, antimony and tin A.  Babbitt metal Q.  Which is the most commonly used bleaching agent? A.  Chlorine Q.  What is the main component of egg shell? A.  Calcium carbonate Q.  Which type of fire extinguisher is used for extinguishing petroleum fire? A.  Powder type Q.  The purest form of carbon is A.  Diamond Q.  A substance which can react chemically as either an acid or a base is known as A.  Amphoteric Q.  Give an example for a Tribasic acid A.  Phosphoric acid Q.  38. What is "White Vitriol"? A.  Zinc Sulfate Q.  Which among the following element is stored under water? A.  White Phosphorous Q.  Cyanide Process is widely used to extract A.  Gold Q.  What is commonly known as "Blue vitriole"? A.  Copper sulfate Q.  Fluorspar is the ore of A.  Calcium Q.  The gas used in refrigerators and ice plants is A.  Ammonia Q.  Carbon monoxide is readily absorbed by A.  Nickel Q.  Synthetic ethanol is produced by reacting ethane (in the presence of phosphoric acid) with A.  Hydrogen Q.  What is called in the bond between two amino acids in protein A.  Peptide bond Q.  Which metal remains in liquid form at normal temperature? A.  Mercury Q.  Common salt (Sodium Chloride) when kept open absorbs moisture from air. This is due to the presence of A.  Magnesium Chloride Q.  The movement or growth of an organism or part of an organism in response to a chemical stimulus A.  Chemotropism Q.  Chemistry in ancient times was called A.  Alchemy Q.  Name a food material which contains phosphorus A.  Onion Q.  Usually, base changes the colour of litmus from A.  Red to Blue Q.  Who discovered penicillin A.  Alexander Fleming Q.  What radioactive element is extracted from carnotite and pitchblende? A.  Uranium. Q.  What color does litmus turn when dipped into acid? A.  Pink. Q.  What is arginine? A.  An amino acid obtained by animals from their diet

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