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Part 061 – Chemistry Previous Year Questions

Q1. How many bones are there in a newly born infant ?
(a) 206 (b) 230
(c) 280 (d) 300
Ans: (c) At birth, there are over 270 bones in an infant body. But many of these fuse together as the child grows, leaving a total of 206 separate bones in a typical adult.

Q2. Radiations which is not emitted during radioactivity is :

(a) rays (b) ravs
(c) ravs (d) Cathode rays
Ans: (d) Radioactivity is the process by which a nucleus of an unstable atom loses energy by emitting particles of ionizing radiation. It includes the emission of energetic alpha particles (), beta particles (), and gamma rays ().

Q3. Citric acid is present in free form in

(a) Tamarind (b) Milk
(c) Apple (d) Lemon
Ans: (d) Lemons, oranges, limes, and other citrus fruits naturally possess high concentrations of citric acid. The juice of the lemon is about 5% to 6% citric acid, which gives lemons a sour taste. In fact, Citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice.

Q4. KMnO4 can be used as

(a) Insecticide (b) Fertilizer
(c) Pesticide (d) Disinfectant
Ans: (d) Potassium permanganate is an inorganic chemical compound with the formula KMnO4. As an oxidant, potassium permanganate can act as an antiseptic. For example, dilute solutions are used to treat canker sores (ulcers), disinfectant for the hands and treatment for mild pompholyx, dermatitis, and fungal infections of the hands or feet. Potassium permanganate is used extensively in the water treatment industry.

Q5. A thick paste of cement, sand and water is called

(a) Concrete (b) R.C.C.
(c) Mortar (d) Kiln
Ans: (c) Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. Modern mortars are typically made from a mixture of sand, a binder such as cement or lime, and water.

Q6. Which of the following is not a chemical reaction’?

(a) Burning of paper
(b) Digestion ot” food
(c) Conversion of water into steam
(d) Burning of coal
Ans: (c) The conversion of water into steam is an example of a physical change, where the state of the matter changes without changing its composition. A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.

Q7. Which of the following is used as anesthetic ?

(a) NH3 (b) NO
(c) NO2 (d) N2O
Ans: (b) Nitrous oxide (NO), commonly known as laughing gas or happy gas, is the most commonly used inhalation anesthetic in dentistry and is commonly used in emergency centers and ambulatory surgery centers as well. It is an inorganic inhalation agent that is colorless, odorless to sweet-smelling, and nonirritating to the tissues.

Q8. The quality of petrol is expressed in terms of

(a) Cetane number
(b) Gold number
(c) Octane number
(d) Added unlead compounds
Ans: (c) Octane rating or octane number is a standard measure of the of the ignition quality of gas (gasoline or petrol). Higher this number, the less susceptible is the gas to ‘knocking’ (explosion caused by its premature burning in the combustion chamber) when burnt in a standard (spark-ignition internal combustion) engine.

Q9. The percentage of litrogen in Air is

(a) 0.94 (b) 0.03
(c) 78.03 (d) 85.02
Ans: (c) By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%.

Q10. Antacids are found in drugs that give relief to

(a) Eye sight
(b) Stomach ache
(c) Acne
(d) Headache
Ans: (b) An antacid is a substance which neutralizes stomach acidity. Antacids are taken by mouth to relieve heartburn, the major symptom of gastro-esophageal reflux disease, or acid indigestion which are a few of the common terms used to describe digestive upset.

Q11. The open “Sigrees” or coal stoves often require fanning to sustain burning because of

(a) tendency of carbon dioxide to form a layer along with dust smoke
(b) lack of oxygen in the surroundings of sigrees
(c) accumulation of smoke and dust over the sigrees
(d) interrupted release of moisture from the material
Ans: (a) Burning coal requires oxygen to chemically react. The availability of oxygen is limited in the furnace by several factors such as the friction of the air against the coal. Blowing provides more oxygen to the flame and raises the temperature of the flame. Besides, it helps to prevent carbon dioxide from forming layer along with dust smoke so as to keep the supply of oxygen intact.

Q12. Browning of paper in old books is caused by

(a) frequent use
(b) lack of aeration
(c) collection of dust
(d) oxidation of cellulose
Ans: (d) Foxing is a term describing the age-related spots and browning seen on vintage paper documents such as books, postage stamps, certificates, and so forth. It results from localized accelerated oxidation of cellulose or the effect on certain papers of the oxidation of iron, copper, etc.

Q13. Aquaregia is a mixture of the following in the ratio 1 : 3 by volume

(a) conc. HNO3 and conc. HCl
(b) conc. HNO3 and conc.
H2SO4
(c) dil. HCl and dil. HNO3
(d) conc. HCl and conc. HNO3
Ans: (c) Aqua regia or nitro-hydrochloric acid is a highly corrosive mixture of acids which is formed by freshly mixing concentrated Nitric acid (HNO3) and Hydrochloric acid (HCl), optimally in a volume ratio of 1:3. It is used in dissolving gold.

Q14. In deep-sea diving, divers use a mixture of gases consisting of oxygen and

(a) hydrogen (b) nitrogen
(c) argon (d) helium
Ans: (b) Air is not the “ideal” breathing mixture for diving as with a concentration of approximately 79 percent nitrogen, compressed air poses two potential problems for all divers: susceptibility to nitrogen narcosis and at deeper depths; and decompression sickness. So divers use Nitrox, a gaseous mixture of nitrogen and oxygen. It is also known as ‘Enriched Air.’

Q15. ‘Atomic theory’ of matter was given by

(a) Avogadro (b) Dalton
(c) Newton (d) Pascal
Ans: (b) Democritus first suggested the existence of the atom, but John Dalton (1766-1844) is credited with the Atomic Theory of Matter. According to Dalton, all matter is made of atoms; atoms are indivisible and indestructible; all atoms of a given element are identical in mass and properties; and compounds are formed by a combination of two or more different kinds of atoms.

Q16. Combustion of a candle is a/an

(a) photochemical reaction
(b) physical change
(c) endothermic reaction
(d) exothermic reaction
Ans: (d) In theory, a candle is made of a solid hydrocarbon called paraffin. When the solid burns, the hydrocarbon reacts with oxygen to form carbon dioxide and water. The reaction is exothermic, meaning it releases heat to the atmosphere along with the other products.

Q17. Which among the following is a covalent compound ?

(a) Calcium chloride
(b) Magnesium fluoride
(c) Sodium chloride
(d) Carbon tetrachloride
Ans: (d) Ionic compounds are made up of a metal and nonmetal, and covalent compounds are made up of two nonmetals. In the carbon tetrachloride molecule, four chlorine atoms are positioned symmetrically as corners in a tetrahedral configuration joined to a central carbon atom by single covalent bonds: CH4 + 4Cl2 ? CCl4 + 4HCl

Q18. The highest volume of gases in lower atmosphere is comprised of

(a) Hydrogen
(b) Carbon dioxide
(c) Oxygen
(d) Nitrogen
Ans: (d) There are a number of atmospheric gases which make up air. In the lower atmosphere or troposphere, the main gases are nitrogen and oxygen, which make up 78% and 21% of the volume of air respectively. The remaining 1% of the atmospheric gases is made up of trace gases.

Q19. The percentage of carbon in cost iron is :

(a) 0.01 to 0.25
(b) 0.5 to 1.5
(c) 6 to 8
(d) 3 to 5
Ans: (d) Cast Iron is a hard, brittle, nonmalleable ironcarbon alloy, cast into shape. It contains 2 to 4.5 percent carbon, 0.5 to 3 percent silicon, and lesser amounts of sulfur, manganese, and phosphorus.

Q20. The compound that has the least value for octane number is :

(a) 2-methyl heptane
(b) Iso-octane
(c) 2,2-dimethyl hexane
(d) n-heptane
Ans: (d) Octane rating or octane number is a standard measure of the performance of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand. Isooctane (upper) has an octane rating of 100 whereas n-heptane has an octane rating of 0.

Q21. The pair of compounds used as anaesthetic in medicines :

(a) Ether, Ammonia
(b) Nitrous oxide, Chloroform
(c) Chloroform, Nitrogen dioxide
(d) Nitrogen dioxide, ether
Ans: (b) Nitrous oxide is one of the more well-known anesthetic gases, and has been in use for around 200 years. Unlike some other anesthetics, this compound can be used both for inducing unconsciousness and pain control. Chloroform is more potent and more toxic than ether. Its use as an anaesthetic decreased with increased experience and knowledge of its dangers.

Q22. pH scale ranges from

(a) 0 – 7 (b) 8 – 14
(c) 0 – 14 (d) None
Ans: (c) The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic. The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value.

Q23. Iron rusts quickly in

(a) Rain water
(b) Sea water
(c) Distilled water
(d) River water
Ans: (b) Water is the enabler of fast oxidation of iron. So freshwater will also cause rust. However, salt water (sea water) is a very good conductor (lots of dissociated ions) and so there are a number of electrolysis reactions that tremendously accelerate corrosion in salt water. This effect can be reversed by using a metal (like zinc) which causes the current to be reversed and in effect the zinc corrodes rapidly, protecting the iron.

Q24. Aerated water contains

(a) SO2 (b) NO2
(c) H2 (d) CO2
Ans: (d) Aerated water is, correctly speaking, water to which air is added. So aerated water is any water artificially impregnated with a large amount of gas (as carbon dioxide). The term is, however, frequently applied to carbonated water.

Q25. Magnetite is

(a) Fe2O3 (b) Fe3O4
(c) FeCO3 (d) 2Fe2O3. 3H2O
Ans: (b) Magnetite is a mineral, one of the two common naturally occurring iron oxides (chemical formula Fe3O4). It is the most magnetic of all the naturally occurring minerals on Earth. The chemical IUPAC name of magnetite is iron oxide and the common chemical name is ferrous-ferric oxide

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