SOME BASIC CONCEPT OF CHEMISTRY.pdf

PRE-MEDICAL Join Telegram: @Chalnaayaaar PHYSICAL CHEMISTRY ENTHUSIAST | LEADER | ACHIEVER EXERCISE Some Basic concept of chemistry ENGLISH MEDIUM  Chem...

PRE-MEDICAL Join Telegram: @Chalnaayaaar PHYSICAL CHEMISTRY ENTHUSIAST | LEADER | ACHIEVER EXERCISE Some Basic concept of chemistry ENGLISH MEDIUM  Chemistry : Some Basic Concept of Chemistry EXERCISE-I (Conceptual Questions) Build Up Your Understanding QUESTIONS BASED ON MOLES 9. Sum of number of protons, electrons and neutrons 12 in 12g of C is :- 1. The number of atoms present in 16 g of oxygen is 6 23 (1) 6.02 × 1011.5 (2) 3.01 × 1023 (1) 1.8 (2) 12.044 × 10 (3) 3.01 × 1011.5 (4) 6.02 × 1023 (3) 1.084 × 1025 (4) 10.84 × 10 23 The number of atoms in 4.25 g of NH3 is approx:- 2. 10. The weight of one atom of Uranium is 238 amu. Its actual weight is.... g. (1) 1 × 10 23 (2) 1.5 × 10 23 (1) 1.43 × 1026 (2) 3.94 × 10 –22 (3) 2 × 10 23 (4) 6 × 1023 (3) 6.99 × 10–23 (4) 1.53 × 10–22 3. Which of the following contains maximum number of oxygen atoms ? 11. The actual weight of a molecule of water is - (1) 1 g of O (1) 18 g –23 (2) 1 g of O2 (2) 2.99 × 10 g (3) 1 g of O3 (3) both (1) & (2) are correct –24 (4) all have the same number of atoms (4) 1.66 × 10 g The number of atoms present in 0.5 g atom of 12. What is the mass of a molecule of CH4 :– 4. nitrogen is same as the atoms in – (1) 16 g (2) 26.6 × 1022 g (1) 12 g of C (2) 32 g of S (3) 2.66 × 10 –23 g (4) 16 NA g (3) 8 g of oxygen (4) 24 g of Mg Which of the following contains maximum number 13. Which of the following has the highest mass ? 5. of atoms ? (1) 1 g atom of C (1) 4 g of H2 (2) 16 g of O2 (2) 1/2 mole of CH4 (3) 28 g of N2 (4) 18 g of H2O (3) 10 mL of water 23 (4) 3.011 × 10 atoms of oxygen Number of neutrons present in 1.7 g of ammonia 6. is - 14. Which of the following contains the least number (1) NA (2) (NA/10) × 4 of molecules ? (3) (NA/10) × 7 (4) NA × 10 × 7 (1) 4.4 g CO2 (2) 3.4 g NH3 (3) 1.6 g CH4 (4) 3.2 g SO2 7. 5.6 L of oxygen at STP contains - (1) 6.02 × 1023 atoms 15. The number of molecule in 4.25 g of NH3 is - 23 (2) 3.01 × 10 atoms (1) 1.505 × 10 23 (2) 3.01 × 1023 23 (3) 1.505 × 10 atoms (3) 6.02 × 1023 (4) None of these 23 (4) 0.7525 × 10 atoms Number of oxygen atoms in 8 g of ozone is - 16. Elements A and B form two compounds B2A3 8. and B2A. 0.05 moles of B2A3 weight 9.0 g and 6.02 × 1023 0.10 mole of B2A weight 10 g. Calculate the (1) 6.02 × 1023 (2) atomic weight of A and B :- 2 (1) 20 and 30 (2) 30 and 40 6.02 × 1023 6.02 × 1023 (3) (4) (3) 40 and 30 (4) 30 and 20 3 6 30  Chemistry : Some Basic Concept of Chemistry 17. 5.6 L of oxygen at NTP is equivalent to – 25. The number of electron in 3.1 mg NO3¯ is (1) 1 mol (2) 1/2 mol (NA = 6 × 1023) (3) 1/4 mol (4) 1/8 mol (1) 32 (2) 1.6 × 10–3 (3) 9.6 × 1020 (4) 9.6 × 1023 18. 4.4 g of an unknown gas occupies 2.24 L of 26. Given that one mole of N2 at NTP occupies volume at STP. The gas may be :- (1) N2O (2) CO 22.4 L the density of N2 is - (3) CO2 (4) 1 & 3 both (1) 1.25 g L–1 (2) 0.80 g L–1 –1 –1 (3) 2.5 g L (4) 1.60 g L 19. Which contains least number of molecules :– 27. The number of carbon atoms present in a (1) 1 g CO2 (2) 1 g N2 signature, if a signature written by carbon pencil, (3) 1 g O2 (4) 1 g H2 weighing 1.2 × 10–3 g is (1) 12.04 × 1020 (2) 6.02 × 1019 20. If V mL of the vapours of substance at NTP (3) 3.01 × 1019 (4) 6.02 × 1020 weight W g. Then molecular weight of substance is:- QUESTIONS BASED ON PERCENTAGE, V (1) (W/V) × 22400 (2) × 22.4 EMPIRICAL FORMULA & MOLECULAR FORMULA W W ×1 28. A compound of X and Y has equal mass of them. (3) (W - V) × 22400 (4) V × 22400 If their atomic weights are 30 and 20 respectively. Molecular formula of the compound is :- 21. If 3.01 × 1020 molecules are removed from (1) X2Y2 (2) X3Y3 (3) X2Y3 (4) X3Y2 98 mg of H2SO4, then the number of moles of 29. An oxide of sulphur contains 50% of sulphur in H2SO4 left are :– it. Its empirical formula is - (1) 0.1 × 10 (2) 0.5 × 10 –3 –3 (1) SO2 (2) SO3 (3) 1.66 × 10–3 (4) 9.95 × 10–2 (3) SO (4) S2O 30. A hydrocarbon contains 80% of carbon, then the 22. A gas is found to have the formula (CO)x. It's VD is 70. The value of x must be:- hydrocarbon is - (1) 7 (2) 4 (3) 5 (4) 6 (1) CH4 (2) C2H4 (3) C2H6 (4) C2H2 23. Vapour density of gas is 11.2. Volume occupied by 2.4 g of this at STP will be - 31. Empirical formula of glucose is - (1) 11.2 L (2) 2.24 L (3) 22.4 L (4) 2.4 L (1) C6H12O6 (2) C3H6O3 (3) C2H4O2 (4) CH2O 24. The volume of a gas in discharge tube is 32. An oxide of metal M has 40% by mass of –7 1.12 × 10 mL at STP. Then the number of molecule of gas in the tube is - oxygen. Metal M has atomic mass of 24. The (1) 3.01 × 10 4 (2) 3.01 × 10 15 empirical formula of the oxide is :- (3) 3.01 × 10 12 (4) 3.01 × 10 16 (1) M2O (2) M2O3 (3) MO (4) M3O4 31  Chemistry : Some Basic Concept of Chemistry 33. A compound contains 38.8% C, 16.0% H and QUESTIONS BASED ON STOICHIOMETRY 45.2% N. The formula of the compound would 41. An organic compound contains carbon, hydrogen be and oxygen. Its elemental analysis gives 38.71% of (1) CH3NH2 (2) CH3CN C and 9.67% of H. The empirical formula of the (3) C2H5CN (4) CH2(NH)2 compound would be :- 34. The simplest formula of a compound containing (1) CHO (2) CH4O 50%(w/w) of element X(at wt. = 10) and 50% of (3) CH3O (4) CH2O element Y(at wt. = 20) is:- (1) XY (2) X2Y (3) XY2 (4) X3Y 42. The amount of water (g) produced by combustion of 286 g of propane is 35. Which of the following compound has same (1) 168 g (2) 200 g empirical formula as that of glucose:- (3) 468 g (4) 693 g (1) CH3CHO (2) CH3COOH (3) CH3OH (4) C2H6 43. In a gaseous reaction of the type 36. 2.2 g of a compound of phosphorous and sulphur aA + bB → cC + dD, has 1.24 g of 'P' in it. Its empirical formula is - which statement is wrong ? (1) P2S3 (2) P3S2 (1) a litre of A combines with b litre of B to give (3) P3S4 (4) P4S3 C and D (2) a mole of A combines with b moles of B to 37. On analysis, a certain compound was found to give C and D contain iodine and oxygen in the mass ratio of 254:80. The formula of the compound is : (3) a g of A combines with b g of B to give (At mass I = 127, O = 16) C and D (1) IO (2) I2O (4) a molecules of A combines with b molecules (3) I5O2 (4) I2O5 of B to give C and D 38. The number of atoms of Cr and O are 4.8 × 1010 44. Assuming that petrol is octane (C8H18) and has 10 and 9.6 × 10 respectively. Its empirical formula –1 density 0.8 g mL. 1.425 L of petrol on is – (1) Cr2O3 (2) CrO2 complete combustion will consume. (3) Cr2O4 (4) CrO5 (1) 50 mole of O2 (2) 100 mole of O2 39. Insulin contains 3.4% sulphur by mass. The (3) 125 mole of O2 minimum molecular weight of insulin is : (4) 200 mole ofO2 (1) 941.176 (2) 944 (3) 945.27 (4) None 45. In a given reaction, 9 g of Al will react with 40. Caffine has a molecular weight of 194. It contains 3 2Al + O2 → Al2 O3 2 28.9% by mass of nitrogen Number of atoms of (1) 6 g O2 (2) 8 g O2 nitrogen in one molecule of it is :- (1) 2 (2) 3 (3) 4 (4) 5 (3) 9 g O2 (4) 4 g O2 32  Chemistry : Some Basic Concept of Chemistry 46. The equation : 51. If 8 mL of uncombined O2 remain after exploding 3 O2 with 4 mL of hydrogen, the number of mL of 2Al(s) + O2(g) → Al2O3(s) shows that :- O2 originally were - 2 (1) 12 (2) 2 3 (1) 2 mol of Al reacts with mol of O2 to produce (3) 10 (4) 4 2 7 mol of Al2O3 2 52. 4 g of hydrogen are ignited with 4 g of oxygen. 3 The weight of water formed is - (2) 2 g of Al reacts with g of O2 to produce 2 (1) 0.5 g (2) 3.5 g one mol of Al2O3 (3) 4.5 g (4) 2.5 g 3 (3) 2 g of Al reacts with L of O2 to produce 2 1 mol of Al2O3 53. For the reaction A + 2B → C, 3 5 mol of A and 8 mol of B will produce (4) 2 mol of Al reacts with mol of O2 to produce 2 (1) 5 mole of C 1 mol of Al2O3 (2) 4 mole of C (3) 8 mole of C 47. 1 L of CO2 is passed over hot coke. When the (4) 13 mole of C volume of reaction mixture becomes 1.4 L, the composition of reaction mixture is– 54. If 1.6 g of SO2 and 1.5 × 1022 molecules of H2S (1) 0.6 L CO are mixed and allowed to remain in contact in a (2) 0.8 L CO2 closed vessel until the reaction (3) 0.6 L CO2 and 0.8 L CO 2H2S + SO2 → 3S + 2H2O, (4) None proceeds to completion. Which of the following statement is true ? (1) Only 'S' and 'H2O' remain in the reaction vessel. 48. 26 cc of CO2 are passed over red hot coke. (2) 'H2S' will remain in excess The volume of CO evolved is :– (3) 'SO2' will remain in excess (1) 15 cc (2) 10 cc (4) None (3) 32 cc (4) 52 cc 55. 12 L of H2 and 11.2 L of Cl2 are mixed and 49. If 1/2 mol of oxygen combine with Aluminium to exploded. The composition by volume of mixture form Al2O3 then weight of Aluminium metal used is– in the reaction is (Al= 27) – (1) 24 L of HCl (g) (1) 27 g (2) 18 g (2) 0.8 L Cl2 and 20.8 L HCl (g) (3) 54 g (4) 40.5 g (3) 0.8 L H2 and 22.4 L HCl (g) (4) 22.4 L HCl (g) 50. If 0.5 mol of BaCl2 is mixed with 0.2 mol of Na3PO4, the maximum number of moles of 56. 10 mL of gaseous hydrocarbon on combustion Ba3(PO4)2 that can be formed is - give 40 mL of CO2(g) and 50 mL of H2O (vap.). 3BaCl2 + 2Na3PO4 → Ba3(PO4)2 + 6NaCl The hydrocarbon is - (1) 0.7 (2) 0.5 (1) C4H5 (2) C8H10 (3) 0.3 (4) 0.1 (3) C4H8 (4) C4H10 33  Chemistry : Some Basic Concept of Chemistry QUESTIONS BASED ON EQUIIVALENT WEIGHTS 64. 0.5 g of a base was completely neutralised by 100 mL of 0.2 N acid. Equivalent weight of the 57. Molecular weight of tribasic acid is W. Its equivalent base is weight will be : (1) 50 (2) 100 (3) 25 (4) 125 W W (1) (2) 2 3 (3) W (4) 3W 65. 0.126 g of an acid requires 20 mL of 0.1 N NaOH for complete neutralisation. Equivalent weight of the acid is – 58. A, E, M and n are the atomic weight, equivalent weight, molecular weight and valency of an (1) 45 (2) 53 (3) 40 (4) 63 element. The correct relation is : M (1) A = E × n (2) A = 66. 2g of a base whose equivalent weight is 40 reacts E with 3 g of an acid. The equivalent weight of the M (3) A = (4) M = A × n acid is : n (1) 40 (2) 60 (3) 10 (4) 80 59. Sulphur forms two chlorides S2Cl2 and SCl2. The equivalent mass of sulphur in SCl2 is 16. The equivalent weight of sulphur in S2Cl2 is - 67. Equivalent weight of a divalent metal is 24. The (1) 8 (2) 16 (3) 32 (4) 64 volume of hydrogen liberated at STP by 12 g of the same metal when added to excess of an acid solution is - 60. If equivalent weight of S in SO2 is 8 then (1) 2.8 litres (2) 5.6 litres equivalent weight of S in SO3 is - (3) 11.2 litres (4) 22.4 litres 8×2 8×3 (1) (2) 3 2 2×3 68. 0.84 g of a metal carbonate reacts exactly with (3) 8 × 2 × 3 (4) 8 40 mL of N/2 H2SO4. The equivalent weight of the metal carbonate is - (1) 84 (2) 64 61. Which property of an element is not variable : (3) 42 (4) 32 (1) Valency (2) Atomic weight (3) Equivalent weight (4) None 69. 1.0 g of a metal combines with 8.89 g of Bromine. Equivalent weight of the metal is nearly : 62. One g equivalent of a substance is present in - (at.wt. of Br = 80) (1) 0.25 mol of O2 (2) 0.5 mol of O2 (1) 8 (2) 9 (3) 1.00 mol of O2 (4) 8.00 mol of O2 (3) 10 (4) 7 63. 0.45 g of acid (molecular wt. = 90) was exactly 70. 0.84 g of metal hydride contains 0.04 g of neutralised by 20 mL of 0.5 N NaOH. Basicity of the acid is - hydrogen. The equivalent wt. of the metal is..... (1) 1 (2) 2 (3) 3 (4) 4 (1) 80 (2) 40 (3) 20 (4) 60 34  Chemistry : Some Basic Concept of Chemistry l 71. When an element forms an oxide in which 78. 1.6 g of Ca and 2.60 g of Zn when treated with oxygen is 20% of the oxide by mass, the an acid in excess separately, produced the same equivalent mass of the element will be – amount of hydrogen. If the equivalent weight of (1) 32 (2) 40 Zn is 32.6, what is the equivalent weight of Ca:- (3) 60 (4) 128 (1) 10 (2) 20 (3) 40 (4) 5 72. 2.8 g of iron displaces 3.2 g of copper from a solution of copper sulphate. If the equivalent 79. 74.5 g of a metallic chloride contains 35.5 g of mass of iron is 28, then equivalent mass of chlorine. The equivalent mass of the metal is – copper will be – (1) 19.5 (2) 35.5 (1) 16 (2) 32 (3) 39.0 (4) 78.0 (3) 48 (4) 64 QUESTIONS BASED ON CALCULATION OF ATOMIC WEIGHTS AND MOLECULAR WEIGHTS 73. If m1 g of a metal A displaces m2 g of another metal B from its salt solution and if their 80. The equivalent weight of a metal is 4. If metal equivalent weight are E2 and E1 respectively then chloride has a vapour density of 59.25. Then the the equivalent weight of A can be expressed by:- valency of metal is – m m (1) 4 (2) 3 (1) 1 × E2 (2) 2 × E2 m2 m1 (3) 2 (4) 1 m1 m2 (3) × E1 (4) × E1 m2 m1 81. –1 –1 Specific heat of a solid element is 0.1 Cal g °C and its equivalent weight is 31.8. Its exact atomic weight is - 74. If 2.4 g of a metal displaces 1.12 L hydrogen at normal temperature and pressure. Equivalent (1) 31.8 (2) 63.6 weight of metal would be:- (3) 318 (4) 95.4 (1) 12 (2) 24 (3) 1.2 × 11.2 (4) 1.2 ÷ 11.2 82. The specific heat of an element is 0.214 Cal g–1 °C–1. The approximate atomic weight is - (1) 0.6 (2) 12 75. 45 g of acid of molecular weight 90 neutralised (3) 30 (4) 65 by 200 mL of 5 N caustic potash. The basicity of the acid is :- (1) 1 (2) 2 83. A metal M forms a sulphate which is (3) 3 (4) None isomorphous with MgSO4.7H2O. If 0.6538 g of metal M displaced 2.16 g of silver from silver nitrate solution, then the atomic weight of the 76. The weights of two elements which combine with metal M is one another are in the ratio of their :– (1) 32.61 (2) 56.82 (1) Atomic weight (2) Molecular weight (3) 65.38 (4) 74.58 (3) Equivalent weight (4) None 84. The carbonate of a metal is isomorphous with MgCO3 and contains 6.091% of carbon. Atomic 77. The oxide of a metal has 32% oxygen. Its weight of the metal is nearly - equivalent weight would be:- (1) 48 (2) 68.5 (1) 34 (2) 32 (3) 17 (4) 16 (3) 137 (4) 120 35  Chemistry : Some Basic Concept of Chemistry 85. 71 g of chlorine combines with a metal giving 94. In Victor Mayer's method, 0.2 g of a volatile 111 g of its chloride. The chloride is isomorphous compound on volatilisation gave 56 mL of vapour with MgCl2.6H2O. The atomic mass of the metal at STP. Its molecular weight is - is:- (1) 40 (2) 60 (3) 80 (4) 120 (1) 20 (2) 30 (3) 40 (4) 69 95. 510 mg of a liquid on vapourisation in 86. The atomic weight of a metal (M) is 27 and its Victor Mayer's apparatus displaces 67.2 cc of dry equivalent weight is 9, the formula of its chloride air (at NTP). The molecular weight of liquid is - will be :- (1) MCl (2) MCl2 (1) 130 (2) 17 (3) 1700 (4) 170 (3) M3Cl (4) MCl3 96. 5 L of gas at STP weighs 6.25 g. What is its 87. The chloride of a metal contains 71% chlorine by gram molecular weight ? weight. If vapour density of metal chloride is 50, (1) 1.25 (2) 14 (3) 28 (4) 56 the atomic weight of the metal will be :- (1) 29 (2) 58 (3) 35.5 (4) 71 97. 0.44 g of a colourless oxide of nitrogen occupies 224 mL at STP. The compound is - 88. –1 The specific heat of a metal M is 0.25 Cal g–1°C. (1) N2O (2) NO (3) N2O4 (4) NO2 Its equivalent weight is 12. What is its correct atomic weight :– (1) 25.6 (2) 36 (3) 24 (4) 12 98. One litre of a certain gas weighs 1.16 g at STP. The gas may be - 89. –1 The density of air at STP is 0.001293 g ml. Its (1) C2H2 (2) CO (3) O2 (4) NH3 vapour density is – (1) 143 (2) 14.3 (3) 1.43 (4) 0.143 99. Equivalent weight of bivalent metal is 32.7. Molecular weight of its chloride is :– 90. Relative density of a volatile substance with (1) 68.2 (2) 103.7 (3) 136.4 (4) 166.3 respect to CH4 is 4. Its molecular weight would be – (1) 8 (2) 32 (3) 64 (4) 128 100. The oxide of an element possess the molecular formula M2O3. If the equivalent mass of the metal is 9, the molecular mass of the oxide will be – 91. Vapour density of a gas is 16. The ratio of specific heat at constant pressure to specific heat (1) 27 (2) 75 (3) 102 (4) 18 at constant volume is 1.4, then its atomic weight is - QUESTIONS BASED ON LAWS OF (1) 8 (2) 16 (3) 24 (4) 32 CHEMICAL COMBINATION 101. The law of multiple proportion was proposed by : 92. The weight of substance that displaces 22.4 L air at NTP is : (1) Lavoisier (2) Dalton (3) Proust (4) Gaylussac (1) Mol. wt. (2) At. wt. (3) Eq. wt. (4) All 102. Which one of the following pairs of compound 93. 0.39 g of a liquid on vapourisation gave 112 mL illustrate the law of multiple proportions ? of vapour at STP. Its molecular weight is - (1) H2O, Na2O (2) MgO, Na2O (1) 39 (2) 18.5 (3) 78 (4) 112 (3) Na2O, BaO (4) SnCl2, SnCl4 36  Chemistry : Some Basic Concept of Chemistry 103. In the reaction N2 + 3H2 → 2 NH3, ratio by 108. The empirical formula of an organic compound volume of N2, H2 and NH3 is 1 : 3 : 2. This containing carbon and hydrogen is CH2. The mass illustrates law of - of one litre of this organic gas is exactly equal to that of one litre of N2 at same temperature and (1) Definite proportion pressure. Therefore, the molecular formula of the (2) Multiple proportion organic gas is – (3) Law of conservation of mass (1) C2H4 (2) C3H6 (4) Gaseous volumes (3) C6H12 (4) C4H8 104. Different proportions of oxygen in the various 109. Four one litre flasks are seperately filled with the oxides of nitrogen prove the law of - gases hydrogen, helium, oxygen and ozone at (1) Equivalent proportion same room temperature and pressure. The ratio (2) Multiple proportion of total number of atoms of these gases present in the different flasks would be - (3) Constant proportion (1) 1 : 1 : 1 : 1 (2) 1 : 2 : 2 : 3 (4) Conservation of matter (3) 2 : 1 : 2 : 3 (4) 2 : 1 : 3 : 2 105. Oxygen combines with two isotopes of carbon 12 C and 14 C to form two sample of carbon 110. A container of volume V, contains 0.28 g of N2 dioxide. The data illustrates - gas. If same volume of an unknown gas under (1) Law of conservation of mass similar condition of temperature and pressure weighs 0.44 g, the molecular mass of the gas is (2) Law of multiple proportions (3) Law of gaseous volume (1) 22 (2) 44 (3) 66 (4) 88 (4) None of these 111. When 100 g of ethylene polymerizes to 106. The law of conservation of mass holds good for polyethylene according to equation all of the following except - nCH2 = CH2 → -(- CH2 - CH2 -)n-. The weight of (1) All chemical reactions polyethylene produced will be:- (2) Nuclear reactions n (1) g (2) 100 g 2 (3) Endothermic reactions 100 (4) Exothermic reactions (3) g (4) 100n g n 107. Number of molecules in 100 mL of each of O2, 112. A chemical equation is balanced according to the NH3 and CO2 at STP are – law of – (1) in the order CO2 < O2 < NH3 (1) Multiple proportion (2) in the order NH3 < O2 < CO2 (2) Constant composition (3) the same (3) Gaseous volume (4) NH3 = CO2 < O2 (4) Conservation of mass 37  Chemistry : Some Basic Concept of Chemistry 113. Two flasks A & B of equal capacity of volume contain NH3 and SO2 gas respectively under similar conditions. Which flask has more number of moles:- (1) A (2) B (3) Both have same moles (4) None EXERCISE-I (Conceptual Questions) ANSWER KEY Que. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ans. 4 4 4 3 1 3 2 2 3 2 2 3 1 4 1 Que. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Ans. 3 3 4 1 1 2 3 4 3 3 1 2 3 1 3 Que. 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Ans. 4 3 1 2 2 4 4 2 1 3 3 3 3 3 2 Que. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Ans. 4 3 4 2 4 3 3 2 3 3 4 2 1 3 1 Que. 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 Ans. 2 1 2 3 4 2 2 3 2 3 1 2 3 2 2 Que. 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 Ans. 3 3 2 3 2 2 3 3 3 3 4 1 3 2 3 Que. 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 Ans. 2 1 3 3 4 3 1 1 3 3 2 4 4 2 4 Que. 106 107 108 109 110 111 112 113 Ans. 2 3 1 3 2 2 4 3 38  Chemistry : Some Basic Concept of Chemistry EXERCISE-II (Previous Year Questions) AIPMT/NEET AIPMT 2009 7. 1.0 g of magnesium is burnt with 0.56 g O2 in a closed vessel. Which reactant is left in excess and 1. 10 g of hydrogen and 64 g of oxygen were filled by how much ? in a steel vessel and exploded. Amount of water (At. wt. Mg = 24 ; O = 16) produced in this reaction will be :- (1) Mg, 0.16 g (2) O2, 0.16 g (1) 1 mol (2) 2 mol (3) Mg, 0.44 g (4) O2, 0.28 g (3) 3 mol (4) 4 mol AIPMT 2015 AIPMT 2010 8. A mixture of gases contains H2 and O2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio 2. The number of atoms in 0.1 mol of a triatomic of the two gases in the mixture ? gas is :- (NA = 6.02 × 1023 mol–1) (1) 4 : 1 (2) 16 : 1 (3) 2 : 1 (4) 1 : 4 22 (1) 1.800 × 10 (2) 6.026 × 1022 (3) 1.806 × 1023 (4) 3.600 × 1023 Re-AIPMT 2015 9. The number of water molecules is maximum in :- AIPMT Mains 2011 (1) 18 g of water (2) 18 mol of water 3. Which has the maximum number of molecules (3) 18 molecules of water among the following ? (4) 1.8 g of water (1) 64 g SO2 (2) 44 g CO2 (3) 48 g O3 (4) 8 g H2 10. If avogadro number NA, is changed from 6.022 × 1023 mol–1 to 6.022 × 1020 mol–1, this NEET UG 2013 would change : (1) the ratio of chemical species to each other in 4. An excess of AgNO3 is added to 100 mL of a 0.01 M a balanced equation solution of dichlorotetraaquachromium(III) chloride. (2) the ratio of elements to each other in a The number of moles of AgCl precipitated would compound be :- (3) the definition of mass in units of grams (1) 0.01 (2) 0.001 (3) 0.002 (4) 0.003 (4) the mass of one mole of carbon 11. 20.0 g of a magnesium carbonate sample AIPMT 2014 decomposes on heating to give carbon dioxide 5. Equal masses of H2,O2 and methane have been and 8.0 g magnesium oxide. What will be the taken in a container of volume V at temeprature percentage purity of magnesium carbonate in the 27°C at identical conditions. The ratio of the sample ? volumes of gases H2 : O2 : CH4 would be : (Atomic weight of Mg = 24) (1) 8 : 16 : 1 (2) 16 : 8 : 1 (1) 60 (2) 84 (3) 75 (4) 96 (3) 16 : 1 : 2 (4) 8 : 1 : 2 NEET-II 2016 12. Suppose the elements X and Y combine to form 6. When 22.4 L of H2(g) is mixed with 11.2 L of two compounds XY2 and X3Y2. When 0.1 mole Cl2(g) at S.T.P., the moles of HCl(g) formed is of XY2 weighs 10 g and 0.05 mole of X3Y2 equal to:- weighs 9 g, the atomic weights of X and Y are (1) 1 mol of HCl (g) (2) 2 mol of HCl (g) (1) 20, 30 (2) 30, 20 (3) 0.5 mol of HCl (g) (4) 1.5 mol of HCl (g) (3) 40, 30 (4) 60, 40 39  Chemistry : Some Basic Concept of Chemistry NEET(UG) 2018 NEET (UG) 2021 13. A mixture of 2.3 g formic acid and 4.5 g oxalic 19. An organic comopound contains 78% (by wt.) acid is treated with conc. H2SO4. The evolved gaseous mixture is passed through KOH pellets. carbon and remaining percentage of hydrogen. Weight (in g) of the remaining product at STP The right option for the empirical formula of this will be H2 SO4 compound is [Atomic wt. of C is 12, H is 1] HCOOH( ) → H2 O( ) + CO(g) H2 SO4 H2 C2 O4 () → H2 O( ) + CO(g) + CO2 (g) (1) CH (2) CH2 (1) 1.4 (2) 3.0 (3) 2.8 (4) 4.4 (3) CH3 (4) CH4 14. In which case is the number of molecules of NEET (UG) 2021 (Paper-2) water maximum? 20. An organic compound on analysis gave C = 54.5%, (1) 18 mL of water H = 9.1% by mass. Its empirical formula is (2) 0.18 g of water (3) 0.00224 L of water vapours at 1 atm and (1) CHO2 (2) CH2O 273 K (3) C2H4O (4) C3H4O –3 (4) 10 mol of water 21. If 1 mL of water contains 20 drops then number NEET (UG) 2019 of molecules in a drop of water is 15. The number of moles of hydrogen molecules (1) 6.023 × 1023 (2) 1.673 × 1021 required to produce 20 moles of ammonia through Haber's process is :- (3) 1.344 × 1018 (4) 4.346 × 1020 (1) 10 (2) 20 (3) 30 (4) 40 22. A sample of phosphorous trichloride (PCl3) NEET (UG) (Odisha) 2019 contains 1.4 moles of the substance. How many 16. The volume occupied by 1.8 g of water vapour atoms are there in the sample? at 374 °C and 1 bar pressure will be :- –1 –1 (1) 4 (2) 5.6 [Use R = 0.083 bar L K mol ] (1) 96.66 L (2) 55.87 L (3) 8.431 × 1023 (4) 3.372 × 1024 (3) 3.10 L (4) 5.37 L NEET (UG) 2020 NEET (UG) 2022 17. Which one of the following has maximum 23. In one molal solution that contains 0.5 mole of a number of atoms? solute, there is (1) 500 g of solvent (1) 1g of Li(s) [Atomic mass of Li = 7] (2) 100 mL of solvent (2) 1g of Ag(s) [Atomic mass of Ag = 108] (3) 1000 g of solvent (3) 1g of Mg(s) [Atomic mass of Mg = 24] (4) 500 mL of solvent (4) 1g of O2(g) [Atomic mass of O = 16] 24. What mass of 95% pure CaCO3 will be required NEET (UG) 2020 (COVID-19) to neutralise 50 mL of 0.5 M HCl solution 18. One mole of carbon atom weighs 12 g, the according to the following reaction ? number of atoms in it is equal to, CaCO3(s)+ 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l) (Mass of carbon – 12 is 1.9926 × 10–23 g) [Calculate upto second place of decimal point] (1) 1.2 × 1023 (2) 6.022 × 10 22 (1) 1.32 g (2) 3.65 g 22 23 (3) 12 × 10 (4) 6.022 × 10 (3) 9.50 g (4) 1.25 g 40  Chemistry : Some Basic Concept of Chemistry NEET (UG) 2022 (OVERSEAS) Re-NEET (UG) 2022 25. Match List-I with List-II : 26. The density of the solution is 2.15 g mL–1, then List-I List-II mass of 2.5 mL solution in correct significant (a) 4.48 litres of (i) 0.2 moles figures is O2 at STP (1) 5375 × 10–3 g (b) 12.022 × 10 22 (ii) 12.044 × 1023 (2) 5.4 g molecules molecules (3) 5.38 g (4) 53.75 g of H2O (c) 96 g of O2 (iii) 6.4 g (d) 88 g of CO2 (iv) 67.2 litres at STP (Given – Molar volume of a gas at STP = 22.4 L) Choose the correct answer from the options given below : (1) (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii) (2) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii) (3) (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv) (4) (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii) EXERCISE-II (Previous Year Questions) ANSWER KEY Que. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ans. 4 3 4 2 3 1 1 1 2 4 2 3 3 1 3 Que. 16 17 18 19 20 21 22 23 24 25 26 Ans. 4 1 4 3 3 2 4 1 1 1 2 41  Chemistry : Some Basic Concept of Chemistry EXERCISE-III (Analytical Questions) Master Your Understanding 1. Number of HCl molecules present in 10 mL of 8. 0.01 mol of iodoform (CHI3) reacts with Ag to 0.1 M solution is : produce a gas whose volume at NTP is 23 (1) 6.022 × 10 (2) 6.023 × 1022 2CHI3 + 6Ag → C2H2 + 6AgI(s) 21 20 (3) 6.022 × 10 (4) 6.022 × 10 (1) 224 mL (2) 112 mL (3) 336 mL (4) None of these 2. The volume of a gas at 0°C and 700 mm 9. The minimum quantity in grams of H2S needed pressure is 760 cc. The no. of molecules present to precipitate 63.5 g of Cu2+ will be nearly : in this volume is 22 23 Cu+2 + H2S → CuS + H2 (1) 1.88 × 10 (2) 6.022 × 10 23 22 (1) 63.5 g (2) 31.75 g (3) 18.8 × 10 (4) 18.8 × 10 (3) 34 g (4) 20 g 10. 2.76 g of silver carbonate on being strongly 3. The number of moles of carbon dioxide which contain 8 g of oxygen is – heated yields a residue weighing – (1) 0.5 mole (2) 0.20 mole Ag2CO3 → 2Ag + CO2 + ½ O2 (3) 0.40 mole (4) 0.25 mole (1) 2.16 g (2) 2.48 g (3) 2.32 g (4) 2.64 g 11. The volume of gas at NTP produced by 100 g of 4. If 224 mL of a triatomic gas has a mass of 1g at CaC2 with water is :- 273 K and 1 atm pressure, then the mass of one CaC2 + 2H2O → Ca(OH)2 + C2H2 atom is – (1) 70 L (2) 35 L (1) 8.30 × 10–23 g (2) 2.08 × 10–23 g (3) 17.5 L (4) 22.4 L –23 (3) 5.53 × 10 g (4) 6.24 × 10–23 g 12. Element 'A' reacts with oxygen to form a compound A2O3. If 0.359 g of 'A' reacts to give 5. The maximum number of molecules are present 0.559 g of the compound, then atomic weight of in 'A' will be :– (1) 5 L of N2 gas at STP (1) 51 (2) 43.08 (3) 49.7 (4) 47.9 (2) 0·5 g of H2 gas (3) 10 g of O2 gas 13. CaCO3 is 90% pure. Volume of CO2 collected at (4) 15 L of H2 gas at STP STP when 10 g of CaCO3 is decomposed is - (1) 2.016 L (2) 1.008 L (3) 10.08 L (4) 20.16 L 6. How many moles of magnesium phosphate, Mg3(PO4)2 will contain 0.25 mol of oxygen 14. 50 g CaCO3 will react with...... g of atoms? 20% pure HCl by weight. (1) 2.5 × 10–2 (2) 0.02 (1) 36.5 g (2) 73 g (3) 3.125 × 10 –2 (4) 1.25 × 10 –2 (3) 109.5 g (4) 182.5 g 15. Two oxides of a metal contains 50% and 40% of 7. 22.4 L of water vapour at NTP, When condensed the metal respectively. The formula of the first to water occupies an approximate volume of - oxide is MO. Then the formula of the second (1) 18 L (2) 1 L oxide is (3) 1 mL (4) 18 mL (1) MO2 (2) M2O3 (3) M2O (4) M2O5 42  Chemistry : Some Basic Concept of Chemistry 16. A gas mixture of 3 L of propane and butane on 23. What volume of oxygen gas (O2) measured at complete combustion at 25°C produces 10 L of 0°C and 1 atm, is needed to burn completely 1L CO2. Initial composition of the propane & of propane gas (C3H8) measured under the same butane in the gas mixture is – conditions:- (1) 66.67%, 33.33% (2) 33.33%, 66.67% (1) 5 L (2) 10 L (3) 50%, 50% (4) 60%, 40% (3) 7 L (4) 6 L 17. The atomic mass of an element is 27. If valency 24. Volume occupied by one molecule of water is 3, the vapour density of the volatile chloride (density =1 gcm–3) is :- will be:- (1) 3.0 × 10 –23 cm3 (2) 5.5 ×10–23 cm3 (1) 66.75 (2) 6.675 (3) 667.5 (4) 81 (3 9.0 × 10 –23 cm 3 (4) 6.023 × 10 –23 cm 3 18. 1 L of a hydrocarbon weighs as much as 1 Lof 25. How many moles of lead (II) chloride will be CO2 under similar conditions. Then the molecular formed from a reaction between 6.5 g of PbO formula of the hydrocarbon is - and 3.2 g of HCl ? (Atomic wt. of Pb=207) (1) C3H8 (2) C2H6 (1) 0.011 (2) 0.029 (3) C2H4 (4) C3H6 (3) 0.044 (4) 0.333 19. There are two oxides of sulphur. They contain 26. The percentage of oxygen in ethanol is 50% and 60% of oxygen respectively by weight. (1) 13.13% (2) 34.73% The weight of sulphur which combine with 1 g of (3) 60% (4) 75% oxygen is in the ratio of - (1) 1 : 1 (2) 2 : 1 27. Empirical formula of a compound is (3) 2 : 3 (4) 3 : 2 (1) Whole number ratio of various atoms present in compound. 20. Perecentage composition of an organic compound (2) Contain exact number of different types of is as follows : atoms present in a molecule. C=10.06, H=0.84 , Cl=89.10 (3) Simplest whole number ratio of various Which of the following corresponds to its molecular atoms present in a compound. formula if the vapour density is 60.0 (4) None of these (1) CH2Cl2 (2) CHCl3 (3) CH3Cl (4) None 28. A compound contains 6.72% hydrogen, 40% carbon and 53.28% oxygen, its molecular 21. The ratio of masses of oxygen and nitrogen in a –1 mass is 180.18 g mol then molecular formula particular gaseous mixture is 1 : 4. The ratio of of compound is :- number of molecules is : (1) C2H2O4 (2) C2H4O12 (1) 1 : 8 (2) 3 : 16 (3) C6H6O12 (4) C6H12O6 (3) 1 : 4 (4) 7 : 32 29. When gases combine or are produced in a 22. A gaseous hydrocarbon on combustion gives chemical reaction they do so in a simple ratio by 0.72 g of water and 3.08 g of CO2. The volume provided all gases are at same empirical formula of the hydrocarbon is temperature and pressure. This law is known as - (1) C2H4 (2) C3H4 (1) Dalton's Law (2) Gay Lussac's Law (3) C6H6 (4) C7H8 (3) Avogadro's Law (4) Law of Lavoisier 43  Chemistry : Some Basic Concept of Chemistry 30. Which of the following reactions is not correct 31. What will be molecular mass of glucose molecule? according to the law of conservation of mass? (1) 342 g (1) 2Mg(s) + O2(g) → 2MgO(s) (2) 180 amu (2) CH4(g) + O2(g) → CO2(g) + H2O(g) 1 (3) Mass exactly equal to of mass of one (3) 4Fe(s) + 3O2(g) → 2Fe2O3(s) 12th (4) P4(s) + 5O2(g) → P4O10(s) C-12 atom (4) Both (2) and (3) EXERCISE-III (Analytical Questions) ANSWER KEY Que. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ans. 4 1 4 3 4 3 4 2 3 1 2 2 1 4 2 Que. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Ans. 1 1 1 4 2 4 4 1 1 2 2 3 4 2 2 Que. 31 Ans. 2 44