Page 1 1.3 Properties of Matter and their Measurement 1. The dimensions of pressure are the same as that of (a) force per unit volume (b) energy per unit volume (c) force (d) energy (1995) 1.4 Uncertainty in Measurement 2. Given the numbers : 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is (a) 3, 3 and 4 respectively (b) 3, 4 and 4 respectively (c) 3, 4 and 5 respectively (d) 3, 3 and 3 respectively. (1998) 1.5 Laws of Chemical Combinations 3. Equal masses of H 2 , O 2 and methane have been taken in a container of volume V at temperature 27 °C in identical conditions. The ratio of the volumes of gases H 2 : O 2 : methane would be (a) 8 : 16 : 1 (b) 16 : 8 : 1 (c) 16 : 1 : 2 (d) 8 : 1 : 2 (2014) 4. What volume of oxygen gas (O 2 ) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C 3 H 8 ) measured under the same conditions? (a) 5 L (b) 10 L (c) 7 L (d) 6 L (2008) 5. 0.24 g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H 2 = 0.089 g/L) (a) 95.93 (b) 59.93 (c) 95.39 (d) 5.993 (1996) 6. The molecular weight of O 2 and SO 2 are 32 and 64 respectively. At 15°C and 150 mmHg pressure, one litre of O 2 contains ‘N’ molecules. The number of molecules in two litres of SO 2 under the same conditions of temperature and pressure will be (a) N/2 (b) N (c) 2 N (d) 4 N (1990) 7. What is the weight of oxygen required for the complete combustion of 2.8 kg of ethylene? (a) 2.8 kg (b) 6.4 kg (c) 9.6 kg (d) 96 kg (1989) 1.7 Atomic and Molecular Masses 8. An element, X has the following isotopic composition : 200 X : 90% 199 X : 8.0% 202 X : 2.0% The weighted average atomic mass of the naturally occurring element X is closest to (a) 201 amu (b) 202 amu (c) 199 amu (d) 200 amu (2007) 9. Boron has two stable isotopes, 10 B(19%) and 11 B(81%). Calculate average at. wt. of boron in the periodic table. (a) 10.8 (b) 10.2 (c) 11.2 (d) 10.0 (1990) 1.8 Mole Concept and Molar Masses 10. Which one of the followings has maximum number of atoms? (a) 1 g of Ag (s) [Atomic mass of Ag = 108] (b) 1 g of Mg (s) [Atomic mass of Mg = 24] (c) 1 g of O 2(g) [Atomic mass of O = 16] (d) 1 g of Li (s) [Atomic mass of Li = 7] (NEET 2020) 11. In which case is number of molecules of water maximum? (a) 18 mL of water (b) 0.18 g of water (c) 0.00224 L of water vapours at 1 atm and 273 K (d) 10 –3 mol of water (NEET 2018) 12. Suppose the elements X and Y combine to form two compounds XY 2 and X 3 Y 2 . When 0.1 mole of XY 2 weighs 10 g and 0.05 mole of X 3 Y 2 weighs 9 g, the atomic weights of X and Y are Some Basic Concepts of Chemistry 1 CHAPTER Page 2 1.3 Properties of Matter and their Measurement 1. The dimensions of pressure are the same as that of (a) force per unit volume (b) energy per unit volume (c) force (d) energy (1995) 1.4 Uncertainty in Measurement 2. Given the numbers : 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is (a) 3, 3 and 4 respectively (b) 3, 4 and 4 respectively (c) 3, 4 and 5 respectively (d) 3, 3 and 3 respectively. (1998) 1.5 Laws of Chemical Combinations 3. Equal masses of H 2 , O 2 and methane have been taken in a container of volume V at temperature 27 °C in identical conditions. The ratio of the volumes of gases H 2 : O 2 : methane would be (a) 8 : 16 : 1 (b) 16 : 8 : 1 (c) 16 : 1 : 2 (d) 8 : 1 : 2 (2014) 4. What volume of oxygen gas (O 2 ) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C 3 H 8 ) measured under the same conditions? (a) 5 L (b) 10 L (c) 7 L (d) 6 L (2008) 5. 0.24 g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H 2 = 0.089 g/L) (a) 95.93 (b) 59.93 (c) 95.39 (d) 5.993 (1996) 6. The molecular weight of O 2 and SO 2 are 32 and 64 respectively. At 15°C and 150 mmHg pressure, one litre of O 2 contains ‘N’ molecules. The number of molecules in two litres of SO 2 under the same conditions of temperature and pressure will be (a) N/2 (b) N (c) 2 N (d) 4 N (1990) 7. What is the weight of oxygen required for the complete combustion of 2.8 kg of ethylene? (a) 2.8 kg (b) 6.4 kg (c) 9.6 kg (d) 96 kg (1989) 1.7 Atomic and Molecular Masses 8. An element, X has the following isotopic composition : 200 X : 90% 199 X : 8.0% 202 X : 2.0% The weighted average atomic mass of the naturally occurring element X is closest to (a) 201 amu (b) 202 amu (c) 199 amu (d) 200 amu (2007) 9. Boron has two stable isotopes, 10 B(19%) and 11 B(81%). Calculate average at. wt. of boron in the periodic table. (a) 10.8 (b) 10.2 (c) 11.2 (d) 10.0 (1990) 1.8 Mole Concept and Molar Masses 10. Which one of the followings has maximum number of atoms? (a) 1 g of Ag (s) [Atomic mass of Ag = 108] (b) 1 g of Mg (s) [Atomic mass of Mg = 24] (c) 1 g of O 2(g) [Atomic mass of O = 16] (d) 1 g of Li (s) [Atomic mass of Li = 7] (NEET 2020) 11. In which case is number of molecules of water maximum? (a) 18 mL of water (b) 0.18 g of water (c) 0.00224 L of water vapours at 1 atm and 273 K (d) 10 –3 mol of water (NEET 2018) 12. Suppose the elements X and Y combine to form two compounds XY 2 and X 3 Y 2 . When 0.1 mole of XY 2 weighs 10 g and 0.05 mole of X 3 Y 2 weighs 9 g, the atomic weights of X and Y are Some Basic Concepts of Chemistry 1 CHAPTER 2 NEET-AIPMT Chapterwise Topicwise Solutions Chemistry (a) 40, 30 (b) 60, 40 (c) 20, 30 (d) 30, 20 (NEET-II 2016) 13. If Avogadro number N A , is changed from 6.022 × 10 23 mol –1 to 6.022 × 10 20 mol –1 , this would change (a) the mass of one mole of carbon (b) the ratio of chemical species to each other in a balanced equation (c) the ratio of elements to each other in a compound (d) the definition of mass in units of grams. (2015) 14. The number of water molecules is maximum in (a) 1.8 gram of water (b) 18 gram of water (c) 18 moles of water (d) 18 molecules of water. (2015) 15. A mixture of gases contains H 2 and O 2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two gases in the mixture? (a) 16 : 1 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1 (2015, Cancelled) 16. Which has the maximum number of molecules among the following? (a) 44 g CO 2 (b) 48 g O 3 (c) 8 g H 2 (d) 64 g SO 2 (Mains 2011) 17. The number of atoms in 0.1 mol of a triatomic gas is (N A = 6.02 × 10 23 mol –1 ) (a) 6.026 × 10 22 (b) 1.806 × 10 23 (c) 3.600 × 10 23 (d) 1.800 × 10 22 (2010) 18. The maximum number of molecules is present in (a) 15 L of H 2 gas at STP (b) 5 L of N 2 gas at STP (c) 0.5 g of H 2 gas (d) 10 g of O 2 gas. (2004) 19. Which has maximum molecules? (a) 7 g N 2 (b) 2 g H 2 (c) 16 g NO 2 (d) 16 g O 2 (2002) 20. Specific volume of cylindrical virus particle is 6.02 × 10 –2 cc/g whose radius and length are 7 Å and 10 Å respectively. If N A = 6.02 × 10 23 , find molecular weight of virus. (a) 15.4 kg/mol (b) 1.54 × 10 4 kg/mol (c) 3.08 × 10 4 kg/mol (d) 3.08 × 10 3 kg/mol (2001) 21. The number of atoms in 4.25 g of NH 3 is approximately (a) 4 × 10 23 (b) 2 × 10 23 (c) 1 × 10 23 (d) 6 × 10 23 (1999) 22. Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of Fe is 56) present in one molecule of haemoglobin is (a) 4 (b) 6 (c) 3 (d) 2 (1998) 23. The number of moles of oxygen in one litre of air containing 21% oxygen by volume, under standard conditions, is (a) 0.0093 mol (b) 2.10 mol (c) 0.186 mol (d) 0.21 mol (1995) 24. The total number of valence electrons in 4.2 g of N 3 – ion is (N A is the Avogadro’s number) (a) 2.1 N A (b) 4.2 N A (c) 1.6 N A (d) 3.2 N A (1994) 25. The number of gram molecules of oxygen in 6.02 × 10 24 CO molecules is (a) 10 g molecules (b) 5 g molecules (c) 1 g molecule (d) 0.5 g molecules. (1990) 26. Ratio of C p and C v of a gas ‘X’ is 1.4. The number of atoms of the gas ‘X’ present in 11.2 litres of it at NTP will be (a) 6.02 × 10 23 (b) 1.2 × 10 23 (c) 3.01 × 10 23 (d) 2.01 × 10 23 (1989) 27. The number of oxygen atoms in 4.4 g of CO 2 is (a) 1.2 × 10 23 (b) 6 × 10 22 (c) 6 × 10 23 (d) 12 × 10 23 (1989) 28. 1 cc N 2 O at NTP contains (a) 18 224 10 22 . × atoms (b) 602 22400 10 23 . × molecules (c) 132 224 10 23 . × electrons (d) all of the above. (1988) 1.9 Percentage Composition 29. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be (a) CHO (b) CH 4 O (c) CH 3 O (d) CH 2 O (2008) 30. Percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (at. wt. = 78.4) then minimum molecular weight of peroxidase anhydrous enzyme is (a) 1.568 × 10 4 (b) 1.568 × 10 3 (c) 15.68 (d) 2.136 × 10 4 (2001) Page 3 1.3 Properties of Matter and their Measurement 1. The dimensions of pressure are the same as that of (a) force per unit volume (b) energy per unit volume (c) force (d) energy (1995) 1.4 Uncertainty in Measurement 2. Given the numbers : 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is (a) 3, 3 and 4 respectively (b) 3, 4 and 4 respectively (c) 3, 4 and 5 respectively (d) 3, 3 and 3 respectively. (1998) 1.5 Laws of Chemical Combinations 3. Equal masses of H 2 , O 2 and methane have been taken in a container of volume V at temperature 27 °C in identical conditions. The ratio of the volumes of gases H 2 : O 2 : methane would be (a) 8 : 16 : 1 (b) 16 : 8 : 1 (c) 16 : 1 : 2 (d) 8 : 1 : 2 (2014) 4. What volume of oxygen gas (O 2 ) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C 3 H 8 ) measured under the same conditions? (a) 5 L (b) 10 L (c) 7 L (d) 6 L (2008) 5. 0.24 g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H 2 = 0.089 g/L) (a) 95.93 (b) 59.93 (c) 95.39 (d) 5.993 (1996) 6. The molecular weight of O 2 and SO 2 are 32 and 64 respectively. At 15°C and 150 mmHg pressure, one litre of O 2 contains ‘N’ molecules. The number of molecules in two litres of SO 2 under the same conditions of temperature and pressure will be (a) N/2 (b) N (c) 2 N (d) 4 N (1990) 7. What is the weight of oxygen required for the complete combustion of 2.8 kg of ethylene? (a) 2.8 kg (b) 6.4 kg (c) 9.6 kg (d) 96 kg (1989) 1.7 Atomic and Molecular Masses 8. An element, X has the following isotopic composition : 200 X : 90% 199 X : 8.0% 202 X : 2.0% The weighted average atomic mass of the naturally occurring element X is closest to (a) 201 amu (b) 202 amu (c) 199 amu (d) 200 amu (2007) 9. Boron has two stable isotopes, 10 B(19%) and 11 B(81%). Calculate average at. wt. of boron in the periodic table. (a) 10.8 (b) 10.2 (c) 11.2 (d) 10.0 (1990) 1.8 Mole Concept and Molar Masses 10. Which one of the followings has maximum number of atoms? (a) 1 g of Ag (s) [Atomic mass of Ag = 108] (b) 1 g of Mg (s) [Atomic mass of Mg = 24] (c) 1 g of O 2(g) [Atomic mass of O = 16] (d) 1 g of Li (s) [Atomic mass of Li = 7] (NEET 2020) 11. In which case is number of molecules of water maximum? (a) 18 mL of water (b) 0.18 g of water (c) 0.00224 L of water vapours at 1 atm and 273 K (d) 10 –3 mol of water (NEET 2018) 12. Suppose the elements X and Y combine to form two compounds XY 2 and X 3 Y 2 . When 0.1 mole of XY 2 weighs 10 g and 0.05 mole of X 3 Y 2 weighs 9 g, the atomic weights of X and Y are Some Basic Concepts of Chemistry 1 CHAPTER 2 NEET-AIPMT Chapterwise Topicwise Solutions Chemistry (a) 40, 30 (b) 60, 40 (c) 20, 30 (d) 30, 20 (NEET-II 2016) 13. If Avogadro number N A , is changed from 6.022 × 10 23 mol –1 to 6.022 × 10 20 mol –1 , this would change (a) the mass of one mole of carbon (b) the ratio of chemical species to each other in a balanced equation (c) the ratio of elements to each other in a compound (d) the definition of mass in units of grams. (2015) 14. The number of water molecules is maximum in (a) 1.8 gram of water (b) 18 gram of water (c) 18 moles of water (d) 18 molecules of water. (2015) 15. A mixture of gases contains H 2 and O 2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two gases in the mixture? (a) 16 : 1 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1 (2015, Cancelled) 16. Which has the maximum number of molecules among the following? (a) 44 g CO 2 (b) 48 g O 3 (c) 8 g H 2 (d) 64 g SO 2 (Mains 2011) 17. The number of atoms in 0.1 mol of a triatomic gas is (N A = 6.02 × 10 23 mol –1 ) (a) 6.026 × 10 22 (b) 1.806 × 10 23 (c) 3.600 × 10 23 (d) 1.800 × 10 22 (2010) 18. The maximum number of molecules is present in (a) 15 L of H 2 gas at STP (b) 5 L of N 2 gas at STP (c) 0.5 g of H 2 gas (d) 10 g of O 2 gas. (2004) 19. Which has maximum molecules? (a) 7 g N 2 (b) 2 g H 2 (c) 16 g NO 2 (d) 16 g O 2 (2002) 20. Specific volume of cylindrical virus particle is 6.02 × 10 –2 cc/g whose radius and length are 7 Å and 10 Å respectively. If N A = 6.02 × 10 23 , find molecular weight of virus. (a) 15.4 kg/mol (b) 1.54 × 10 4 kg/mol (c) 3.08 × 10 4 kg/mol (d) 3.08 × 10 3 kg/mol (2001) 21. The number of atoms in 4.25 g of NH 3 is approximately (a) 4 × 10 23 (b) 2 × 10 23 (c) 1 × 10 23 (d) 6 × 10 23 (1999) 22. Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of Fe is 56) present in one molecule of haemoglobin is (a) 4 (b) 6 (c) 3 (d) 2 (1998) 23. The number of moles of oxygen in one litre of air containing 21% oxygen by volume, under standard conditions, is (a) 0.0093 mol (b) 2.10 mol (c) 0.186 mol (d) 0.21 mol (1995) 24. The total number of valence electrons in 4.2 g of N 3 – ion is (N A is the Avogadro’s number) (a) 2.1 N A (b) 4.2 N A (c) 1.6 N A (d) 3.2 N A (1994) 25. The number of gram molecules of oxygen in 6.02 × 10 24 CO molecules is (a) 10 g molecules (b) 5 g molecules (c) 1 g molecule (d) 0.5 g molecules. (1990) 26. Ratio of C p and C v of a gas ‘X’ is 1.4. The number of atoms of the gas ‘X’ present in 11.2 litres of it at NTP will be (a) 6.02 × 10 23 (b) 1.2 × 10 23 (c) 3.01 × 10 23 (d) 2.01 × 10 23 (1989) 27. The number of oxygen atoms in 4.4 g of CO 2 is (a) 1.2 × 10 23 (b) 6 × 10 22 (c) 6 × 10 23 (d) 12 × 10 23 (1989) 28. 1 cc N 2 O at NTP contains (a) 18 224 10 22 . × atoms (b) 602 22400 10 23 . × molecules (c) 132 224 10 23 . × electrons (d) all of the above. (1988) 1.9 Percentage Composition 29. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be (a) CHO (b) CH 4 O (c) CH 3 O (d) CH 2 O (2008) 30. Percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (at. wt. = 78.4) then minimum molecular weight of peroxidase anhydrous enzyme is (a) 1.568 × 10 4 (b) 1.568 × 10 3 (c) 15.68 (d) 2.136 × 10 4 (2001) 3 Some Basic Concepts of Chemistry 31. Which of the following fertilizers has the highest nitrogen percentage? (a) Ammonium sulphate (b) Calcium cyanamide (c) Urea (d) Ammonium nitrate (1993) 1.10 Stoichiometry and Stoichiometric Calculations 32. The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is (a) 40 (b) 10 (c) 20 (d) 30 (NEET 2019) 33. The density of 2 M aqueous solution of NaOH is 1.28 g/cm 3 . The molality of the solution is [Given that molecular mass of NaOH = 40 g mol –1 ] (a) 1.20 m (b) 1.56 m (c) 1.67 m (d) 1.32 m (Odisha NEET 2019) 34. A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H 2 SO 4 . The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be (a) 1.4 (b) 3.0 (c) 2.8 (d) 4.4 (NEET 2018) 35. What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO 3 is mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5) (a) 3.5 g (b) 7 g (c) 14 g (d) 28 g (2015) 36. 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (At. wt. of Mg = 24) (a) 96 (b) 60 (c) 84 (d) 75 (2015) 37. When 22.4 litres of H 2(g) is mixed with 11.2 litres of Cl 2(g) , each at STP, the moles of HCl (g) formed is equal to (a) 1 mol of HCl (g) (b) 2 mol of HCl (g) (c) 0.5 mol of HCl (g) (d) 1.5 mol of HCl (g) (2014) 38. 1.0 g of magnesium is burnt with 0.56 g O 2 in a closed vessel. Which reactant is left in excess and how much? (At. wt. Mg = 24, O = 16) (a) Mg, 0.16 g (b) O 2 , 0.16 g (c) Mg, 0.44 g (d) O 2 , 0.28 g (2014) 39. 6.02 × 10 20 molecules of urea are present in 100 mL of its solution. The concentration of solution is (a) 0.001 M (b) 0.1 M (c) 0.02 M (d) 0.01 M (NEET 2013) 40. In an experiment it showed that 10 mL of 0.05 M solution of chloride required 10 mL of 0.1 M solution of AgNO 3 , which of the following will be the formula of the chloride (X stands for the symbol of the element other than chlorine)? (a) X 2 Cl 2 (b) XCl 2 (c) XCl 4 (d) X 2 Cl (Karnataka NEET 2013) 41. 25.3 g of sodium carbonate, Na 2 CO 3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na + and carbonate ions, CO 3 2– are respectively (Molar mass of Na 2 CO 3 = 106 g mol –1 ) (a) 0.955 M and 1.910 M (b) 1.910 M and 0.955 M (c) 1.90 M and 1.910 M (d) 0.477 M and 0.477 M (2010) 42. 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be (a) 3 mol (b) 4 mol (c) 1 mol (d) 2 mol (2009) 43. How many moles of lead(II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g HCl? (a) 0.011 (b) 0.029 (c) 0.044 (d) 0.333 (2008) 44. The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (a) 270 kg (b) 540 kg (c) 90 kg (d) 180 kg (Atomic mass : Al = 27) (2005) 45. Molarity of liquid HCl, if density of solution is 1.17 g/cc is (a) 36.5 (b) 18.25 (c) 32.05 (d) 42.10 (2001) 46. Volume of CO 2 obtained by the complete decomposition of 9.85 g of BaCO 3 is (a) 2.24 L (b) 1.12 L (c) 0.84 L (d) 0.56 L (2000) Page 4 1.3 Properties of Matter and their Measurement 1. The dimensions of pressure are the same as that of (a) force per unit volume (b) energy per unit volume (c) force (d) energy (1995) 1.4 Uncertainty in Measurement 2. Given the numbers : 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is (a) 3, 3 and 4 respectively (b) 3, 4 and 4 respectively (c) 3, 4 and 5 respectively (d) 3, 3 and 3 respectively. (1998) 1.5 Laws of Chemical Combinations 3. Equal masses of H 2 , O 2 and methane have been taken in a container of volume V at temperature 27 °C in identical conditions. The ratio of the volumes of gases H 2 : O 2 : methane would be (a) 8 : 16 : 1 (b) 16 : 8 : 1 (c) 16 : 1 : 2 (d) 8 : 1 : 2 (2014) 4. What volume of oxygen gas (O 2 ) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C 3 H 8 ) measured under the same conditions? (a) 5 L (b) 10 L (c) 7 L (d) 6 L (2008) 5. 0.24 g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H 2 = 0.089 g/L) (a) 95.93 (b) 59.93 (c) 95.39 (d) 5.993 (1996) 6. The molecular weight of O 2 and SO 2 are 32 and 64 respectively. At 15°C and 150 mmHg pressure, one litre of O 2 contains ‘N’ molecules. The number of molecules in two litres of SO 2 under the same conditions of temperature and pressure will be (a) N/2 (b) N (c) 2 N (d) 4 N (1990) 7. What is the weight of oxygen required for the complete combustion of 2.8 kg of ethylene? (a) 2.8 kg (b) 6.4 kg (c) 9.6 kg (d) 96 kg (1989) 1.7 Atomic and Molecular Masses 8. An element, X has the following isotopic composition : 200 X : 90% 199 X : 8.0% 202 X : 2.0% The weighted average atomic mass of the naturally occurring element X is closest to (a) 201 amu (b) 202 amu (c) 199 amu (d) 200 amu (2007) 9. Boron has two stable isotopes, 10 B(19%) and 11 B(81%). Calculate average at. wt. of boron in the periodic table. (a) 10.8 (b) 10.2 (c) 11.2 (d) 10.0 (1990) 1.8 Mole Concept and Molar Masses 10. Which one of the followings has maximum number of atoms? (a) 1 g of Ag (s) [Atomic mass of Ag = 108] (b) 1 g of Mg (s) [Atomic mass of Mg = 24] (c) 1 g of O 2(g) [Atomic mass of O = 16] (d) 1 g of Li (s) [Atomic mass of Li = 7] (NEET 2020) 11. In which case is number of molecules of water maximum? (a) 18 mL of water (b) 0.18 g of water (c) 0.00224 L of water vapours at 1 atm and 273 K (d) 10 –3 mol of water (NEET 2018) 12. Suppose the elements X and Y combine to form two compounds XY 2 and X 3 Y 2 . When 0.1 mole of XY 2 weighs 10 g and 0.05 mole of X 3 Y 2 weighs 9 g, the atomic weights of X and Y are Some Basic Concepts of Chemistry 1 CHAPTER 2 NEET-AIPMT Chapterwise Topicwise Solutions Chemistry (a) 40, 30 (b) 60, 40 (c) 20, 30 (d) 30, 20 (NEET-II 2016) 13. If Avogadro number N A , is changed from 6.022 × 10 23 mol –1 to 6.022 × 10 20 mol –1 , this would change (a) the mass of one mole of carbon (b) the ratio of chemical species to each other in a balanced equation (c) the ratio of elements to each other in a compound (d) the definition of mass in units of grams. (2015) 14. The number of water molecules is maximum in (a) 1.8 gram of water (b) 18 gram of water (c) 18 moles of water (d) 18 molecules of water. (2015) 15. A mixture of gases contains H 2 and O 2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two gases in the mixture? (a) 16 : 1 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1 (2015, Cancelled) 16. Which has the maximum number of molecules among the following? (a) 44 g CO 2 (b) 48 g O 3 (c) 8 g H 2 (d) 64 g SO 2 (Mains 2011) 17. The number of atoms in 0.1 mol of a triatomic gas is (N A = 6.02 × 10 23 mol –1 ) (a) 6.026 × 10 22 (b) 1.806 × 10 23 (c) 3.600 × 10 23 (d) 1.800 × 10 22 (2010) 18. The maximum number of molecules is present in (a) 15 L of H 2 gas at STP (b) 5 L of N 2 gas at STP (c) 0.5 g of H 2 gas (d) 10 g of O 2 gas. (2004) 19. Which has maximum molecules? (a) 7 g N 2 (b) 2 g H 2 (c) 16 g NO 2 (d) 16 g O 2 (2002) 20. Specific volume of cylindrical virus particle is 6.02 × 10 –2 cc/g whose radius and length are 7 Å and 10 Å respectively. If N A = 6.02 × 10 23 , find molecular weight of virus. (a) 15.4 kg/mol (b) 1.54 × 10 4 kg/mol (c) 3.08 × 10 4 kg/mol (d) 3.08 × 10 3 kg/mol (2001) 21. The number of atoms in 4.25 g of NH 3 is approximately (a) 4 × 10 23 (b) 2 × 10 23 (c) 1 × 10 23 (d) 6 × 10 23 (1999) 22. Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of Fe is 56) present in one molecule of haemoglobin is (a) 4 (b) 6 (c) 3 (d) 2 (1998) 23. The number of moles of oxygen in one litre of air containing 21% oxygen by volume, under standard conditions, is (a) 0.0093 mol (b) 2.10 mol (c) 0.186 mol (d) 0.21 mol (1995) 24. The total number of valence electrons in 4.2 g of N 3 – ion is (N A is the Avogadro’s number) (a) 2.1 N A (b) 4.2 N A (c) 1.6 N A (d) 3.2 N A (1994) 25. The number of gram molecules of oxygen in 6.02 × 10 24 CO molecules is (a) 10 g molecules (b) 5 g molecules (c) 1 g molecule (d) 0.5 g molecules. (1990) 26. Ratio of C p and C v of a gas ‘X’ is 1.4. The number of atoms of the gas ‘X’ present in 11.2 litres of it at NTP will be (a) 6.02 × 10 23 (b) 1.2 × 10 23 (c) 3.01 × 10 23 (d) 2.01 × 10 23 (1989) 27. The number of oxygen atoms in 4.4 g of CO 2 is (a) 1.2 × 10 23 (b) 6 × 10 22 (c) 6 × 10 23 (d) 12 × 10 23 (1989) 28. 1 cc N 2 O at NTP contains (a) 18 224 10 22 . × atoms (b) 602 22400 10 23 . × molecules (c) 132 224 10 23 . × electrons (d) all of the above. (1988) 1.9 Percentage Composition 29. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be (a) CHO (b) CH 4 O (c) CH 3 O (d) CH 2 O (2008) 30. Percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (at. wt. = 78.4) then minimum molecular weight of peroxidase anhydrous enzyme is (a) 1.568 × 10 4 (b) 1.568 × 10 3 (c) 15.68 (d) 2.136 × 10 4 (2001) 3 Some Basic Concepts of Chemistry 31. Which of the following fertilizers has the highest nitrogen percentage? (a) Ammonium sulphate (b) Calcium cyanamide (c) Urea (d) Ammonium nitrate (1993) 1.10 Stoichiometry and Stoichiometric Calculations 32. The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is (a) 40 (b) 10 (c) 20 (d) 30 (NEET 2019) 33. The density of 2 M aqueous solution of NaOH is 1.28 g/cm 3 . The molality of the solution is [Given that molecular mass of NaOH = 40 g mol –1 ] (a) 1.20 m (b) 1.56 m (c) 1.67 m (d) 1.32 m (Odisha NEET 2019) 34. A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H 2 SO 4 . The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be (a) 1.4 (b) 3.0 (c) 2.8 (d) 4.4 (NEET 2018) 35. What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO 3 is mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5) (a) 3.5 g (b) 7 g (c) 14 g (d) 28 g (2015) 36. 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (At. wt. of Mg = 24) (a) 96 (b) 60 (c) 84 (d) 75 (2015) 37. When 22.4 litres of H 2(g) is mixed with 11.2 litres of Cl 2(g) , each at STP, the moles of HCl (g) formed is equal to (a) 1 mol of HCl (g) (b) 2 mol of HCl (g) (c) 0.5 mol of HCl (g) (d) 1.5 mol of HCl (g) (2014) 38. 1.0 g of magnesium is burnt with 0.56 g O 2 in a closed vessel. Which reactant is left in excess and how much? (At. wt. Mg = 24, O = 16) (a) Mg, 0.16 g (b) O 2 , 0.16 g (c) Mg, 0.44 g (d) O 2 , 0.28 g (2014) 39. 6.02 × 10 20 molecules of urea are present in 100 mL of its solution. The concentration of solution is (a) 0.001 M (b) 0.1 M (c) 0.02 M (d) 0.01 M (NEET 2013) 40. In an experiment it showed that 10 mL of 0.05 M solution of chloride required 10 mL of 0.1 M solution of AgNO 3 , which of the following will be the formula of the chloride (X stands for the symbol of the element other than chlorine)? (a) X 2 Cl 2 (b) XCl 2 (c) XCl 4 (d) X 2 Cl (Karnataka NEET 2013) 41. 25.3 g of sodium carbonate, Na 2 CO 3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na + and carbonate ions, CO 3 2– are respectively (Molar mass of Na 2 CO 3 = 106 g mol –1 ) (a) 0.955 M and 1.910 M (b) 1.910 M and 0.955 M (c) 1.90 M and 1.910 M (d) 0.477 M and 0.477 M (2010) 42. 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be (a) 3 mol (b) 4 mol (c) 1 mol (d) 2 mol (2009) 43. How many moles of lead(II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g HCl? (a) 0.011 (b) 0.029 (c) 0.044 (d) 0.333 (2008) 44. The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (a) 270 kg (b) 540 kg (c) 90 kg (d) 180 kg (Atomic mass : Al = 27) (2005) 45. Molarity of liquid HCl, if density of solution is 1.17 g/cc is (a) 36.5 (b) 18.25 (c) 32.05 (d) 42.10 (2001) 46. Volume of CO 2 obtained by the complete decomposition of 9.85 g of BaCO 3 is (a) 2.24 L (b) 1.12 L (c) 0.84 L (d) 0.56 L (2000) 4 NEET-AIPMT Chapterwise Topicwise Solutions Chemistry 47. In the reaction, 4NH 3(g) + 5O 2(g) ? 4NO (g) + 6H 2 O (l) when 1 mole of ammonia and 1 mole of O 2 are made to react to completion (a) all the oxygen will be consumed (b) 1.0 mole of NO will be produced (c) 1.0 mole of H 2 O is produced (d) all the ammonia will be consumed. (1998) 48. The amount of zinc required to produce 224 mL of H 2 at STP on treatment with dilute H 2 SO 4 will be (a) 65 g (b) 0.065 g (c) 0.65 g (d) 6.5 g (1996) 49. At STP the density of CCl 4 vapour in g/L will be nearest to (a) 6.87 (b) 3.42 (c) 10.26 (d) 4.57 (1988) ANSWER KEY 1. (b) 2. (d) 3. (c) 4. (a) 5. (b) 6. (c) 7. (c) 8. (d) 9. (a) 10. (d) 11. (a) 12. (a) 13. (a) 14. (c) 15. (d) 16. (c) 17. (b) 18. (a) 19. (b) 20. (a) 21. (d) 22. (a) 23. (a) 24. (c) 25. (b) 26. (a) 27. (a) 28. (d) 29. (c) 30. (a) 31. (c) 32. (d) 33. (c) 34. (c) 35. (b) 36. (c) 37. (a) 38. (a) 39. (d) 40. (b) 41. (b) 42. (b) 43. (b) 44. (c) 45. (c) 46. (b) 47. (a) 48. (c) 49. (a) 1. (b) : Pressure= Force Area Therefore, dimensions of pressure = - MLT L 2 2 = ML –1 T –2 and dimensions of energy per unit volume = = = - -- Energy Volume ML T L ML T 3 22 12 2. (d) : Zeros placed left to the number are never significant, therefore the no. of significant figures for the numbers 161 cm, 0.161 cm and 0.0161 cm are same, i.e., 3. 3. (c) : According to Avogadro’s hypothesis, ratio of the volumes of gases will be equal to the ratio of their no. of moles. So no. of moles = Mass Mol. mass , n w n w n w H O CH 2 2 4 2 32 16 = = = ; ; So, the ratio is or ww w 23216 1612 : : :: . 4. (a) : C 3 H 8 + 5O 2 3CO 2 + 4H 2 O 1 vol. 5 vol. 3 vol. 4 vol. According to the above equation, 1 vol. or 1 litre of propane requires 5 vol. or 5 litres of O 2 to burn completely. 5. (b) : Weight of gas = 0.24 g, Volume of gas = 45 mL = 0.045 litre and density of H 2 = 0.089 g/L Weight of 45 mL of H 2 = density × volume = 0.089 × 0.045 = 4.005 × 10 –3 g Therefore, vapour density = Weight of certain volume of substance Weight of same volume e of hydrogen = × = - 024 4 005 10 59 93 3 . . . 6. (c) : If 1 L of one gas contains N molecules, 2 L of any gas under the same conditions will contain 2N molecules. 7. (c) : C 2 H 4 + 3O 2 ? 2CO 2 + 2H 2 O 28 g 96 g For complete combustion, 2.8 kg of C 2 H 4 requires =× × 96 28 28 10 3 . g = 9.6 × 10 3 g = 9.6 kg of O 2 8. (d) : Average isotopic mass of X = ×+ ×+ × ++ 200 90 1998 202 2 9082 = ++ = ˜ 18000 1592 404 100 199 96 . amu 200 amu 9. (a) : A verage atomic mass = ×+× = 19 10 81 11 100 10 81 . 10. (d) : 1 mole of substance = N A atoms 108 g of Ag = N A atoms ? = 1gof Ag atoms N A 108 24 g of Mg = N A atoms ? = 1gof Mg atoms N A 24 32 g of O 2 = N A molecules = 2 N A atoms ? = 1gof O atoms 2 N A 16 Hints & Explanations Page 5 1.3 Properties of Matter and their Measurement 1. The dimensions of pressure are the same as that of (a) force per unit volume (b) energy per unit volume (c) force (d) energy (1995) 1.4 Uncertainty in Measurement 2. Given the numbers : 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is (a) 3, 3 and 4 respectively (b) 3, 4 and 4 respectively (c) 3, 4 and 5 respectively (d) 3, 3 and 3 respectively. (1998) 1.5 Laws of Chemical Combinations 3. Equal masses of H 2 , O 2 and methane have been taken in a container of volume V at temperature 27 °C in identical conditions. The ratio of the volumes of gases H 2 : O 2 : methane would be (a) 8 : 16 : 1 (b) 16 : 8 : 1 (c) 16 : 1 : 2 (d) 8 : 1 : 2 (2014) 4. What volume of oxygen gas (O 2 ) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C 3 H 8 ) measured under the same conditions? (a) 5 L (b) 10 L (c) 7 L (d) 6 L (2008) 5. 0.24 g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H 2 = 0.089 g/L) (a) 95.93 (b) 59.93 (c) 95.39 (d) 5.993 (1996) 6. The molecular weight of O 2 and SO 2 are 32 and 64 respectively. At 15°C and 150 mmHg pressure, one litre of O 2 contains ‘N’ molecules. The number of molecules in two litres of SO 2 under the same conditions of temperature and pressure will be (a) N/2 (b) N (c) 2 N (d) 4 N (1990) 7. What is the weight of oxygen required for the complete combustion of 2.8 kg of ethylene? (a) 2.8 kg (b) 6.4 kg (c) 9.6 kg (d) 96 kg (1989) 1.7 Atomic and Molecular Masses 8. An element, X has the following isotopic composition : 200 X : 90% 199 X : 8.0% 202 X : 2.0% The weighted average atomic mass of the naturally occurring element X is closest to (a) 201 amu (b) 202 amu (c) 199 amu (d) 200 amu (2007) 9. Boron has two stable isotopes, 10 B(19%) and 11 B(81%). Calculate average at. wt. of boron in the periodic table. (a) 10.8 (b) 10.2 (c) 11.2 (d) 10.0 (1990) 1.8 Mole Concept and Molar Masses 10. Which one of the followings has maximum number of atoms? (a) 1 g of Ag (s) [Atomic mass of Ag = 108] (b) 1 g of Mg (s) [Atomic mass of Mg = 24] (c) 1 g of O 2(g) [Atomic mass of O = 16] (d) 1 g of Li (s) [Atomic mass of Li = 7] (NEET 2020) 11. In which case is number of molecules of water maximum? (a) 18 mL of water (b) 0.18 g of water (c) 0.00224 L of water vapours at 1 atm and 273 K (d) 10 –3 mol of water (NEET 2018) 12. Suppose the elements X and Y combine to form two compounds XY 2 and X 3 Y 2 . When 0.1 mole of XY 2 weighs 10 g and 0.05 mole of X 3 Y 2 weighs 9 g, the atomic weights of X and Y are Some Basic Concepts of Chemistry 1 CHAPTER 2 NEET-AIPMT Chapterwise Topicwise Solutions Chemistry (a) 40, 30 (b) 60, 40 (c) 20, 30 (d) 30, 20 (NEET-II 2016) 13. If Avogadro number N A , is changed from 6.022 × 10 23 mol –1 to 6.022 × 10 20 mol –1 , this would change (a) the mass of one mole of carbon (b) the ratio of chemical species to each other in a balanced equation (c) the ratio of elements to each other in a compound (d) the definition of mass in units of grams. (2015) 14. The number of water molecules is maximum in (a) 1.8 gram of water (b) 18 gram of water (c) 18 moles of water (d) 18 molecules of water. (2015) 15. A mixture of gases contains H 2 and O 2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two gases in the mixture? (a) 16 : 1 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1 (2015, Cancelled) 16. Which has the maximum number of molecules among the following? (a) 44 g CO 2 (b) 48 g O 3 (c) 8 g H 2 (d) 64 g SO 2 (Mains 2011) 17. The number of atoms in 0.1 mol of a triatomic gas is (N A = 6.02 × 10 23 mol –1 ) (a) 6.026 × 10 22 (b) 1.806 × 10 23 (c) 3.600 × 10 23 (d) 1.800 × 10 22 (2010) 18. The maximum number of molecules is present in (a) 15 L of H 2 gas at STP (b) 5 L of N 2 gas at STP (c) 0.5 g of H 2 gas (d) 10 g of O 2 gas. (2004) 19. Which has maximum molecules? (a) 7 g N 2 (b) 2 g H 2 (c) 16 g NO 2 (d) 16 g O 2 (2002) 20. Specific volume of cylindrical virus particle is 6.02 × 10 –2 cc/g whose radius and length are 7 Å and 10 Å respectively. If N A = 6.02 × 10 23 , find molecular weight of virus. (a) 15.4 kg/mol (b) 1.54 × 10 4 kg/mol (c) 3.08 × 10 4 kg/mol (d) 3.08 × 10 3 kg/mol (2001) 21. The number of atoms in 4.25 g of NH 3 is approximately (a) 4 × 10 23 (b) 2 × 10 23 (c) 1 × 10 23 (d) 6 × 10 23 (1999) 22. Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of Fe is 56) present in one molecule of haemoglobin is (a) 4 (b) 6 (c) 3 (d) 2 (1998) 23. The number of moles of oxygen in one litre of air containing 21% oxygen by volume, under standard conditions, is (a) 0.0093 mol (b) 2.10 mol (c) 0.186 mol (d) 0.21 mol (1995) 24. The total number of valence electrons in 4.2 g of N 3 – ion is (N A is the Avogadro’s number) (a) 2.1 N A (b) 4.2 N A (c) 1.6 N A (d) 3.2 N A (1994) 25. The number of gram molecules of oxygen in 6.02 × 10 24 CO molecules is (a) 10 g molecules (b) 5 g molecules (c) 1 g molecule (d) 0.5 g molecules. (1990) 26. Ratio of C p and C v of a gas ‘X’ is 1.4. The number of atoms of the gas ‘X’ present in 11.2 litres of it at NTP will be (a) 6.02 × 10 23 (b) 1.2 × 10 23 (c) 3.01 × 10 23 (d) 2.01 × 10 23 (1989) 27. The number of oxygen atoms in 4.4 g of CO 2 is (a) 1.2 × 10 23 (b) 6 × 10 22 (c) 6 × 10 23 (d) 12 × 10 23 (1989) 28. 1 cc N 2 O at NTP contains (a) 18 224 10 22 . × atoms (b) 602 22400 10 23 . × molecules (c) 132 224 10 23 . × electrons (d) all of the above. (1988) 1.9 Percentage Composition 29. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be (a) CHO (b) CH 4 O (c) CH 3 O (d) CH 2 O (2008) 30. Percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (at. wt. = 78.4) then minimum molecular weight of peroxidase anhydrous enzyme is (a) 1.568 × 10 4 (b) 1.568 × 10 3 (c) 15.68 (d) 2.136 × 10 4 (2001) 3 Some Basic Concepts of Chemistry 31. Which of the following fertilizers has the highest nitrogen percentage? (a) Ammonium sulphate (b) Calcium cyanamide (c) Urea (d) Ammonium nitrate (1993) 1.10 Stoichiometry and Stoichiometric Calculations 32. The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is (a) 40 (b) 10 (c) 20 (d) 30 (NEET 2019) 33. The density of 2 M aqueous solution of NaOH is 1.28 g/cm 3 . The molality of the solution is [Given that molecular mass of NaOH = 40 g mol –1 ] (a) 1.20 m (b) 1.56 m (c) 1.67 m (d) 1.32 m (Odisha NEET 2019) 34. A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H 2 SO 4 . The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be (a) 1.4 (b) 3.0 (c) 2.8 (d) 4.4 (NEET 2018) 35. What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO 3 is mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5) (a) 3.5 g (b) 7 g (c) 14 g (d) 28 g (2015) 36. 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (At. wt. of Mg = 24) (a) 96 (b) 60 (c) 84 (d) 75 (2015) 37. When 22.4 litres of H 2(g) is mixed with 11.2 litres of Cl 2(g) , each at STP, the moles of HCl (g) formed is equal to (a) 1 mol of HCl (g) (b) 2 mol of HCl (g) (c) 0.5 mol of HCl (g) (d) 1.5 mol of HCl (g) (2014) 38. 1.0 g of magnesium is burnt with 0.56 g O 2 in a closed vessel. Which reactant is left in excess and how much? (At. wt. Mg = 24, O = 16) (a) Mg, 0.16 g (b) O 2 , 0.16 g (c) Mg, 0.44 g (d) O 2 , 0.28 g (2014) 39. 6.02 × 10 20 molecules of urea are present in 100 mL of its solution. The concentration of solution is (a) 0.001 M (b) 0.1 M (c) 0.02 M (d) 0.01 M (NEET 2013) 40. In an experiment it showed that 10 mL of 0.05 M solution of chloride required 10 mL of 0.1 M solution of AgNO 3 , which of the following will be the formula of the chloride (X stands for the symbol of the element other than chlorine)? (a) X 2 Cl 2 (b) XCl 2 (c) XCl 4 (d) X 2 Cl (Karnataka NEET 2013) 41. 25.3 g of sodium carbonate, Na 2 CO 3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na + and carbonate ions, CO 3 2– are respectively (Molar mass of Na 2 CO 3 = 106 g mol –1 ) (a) 0.955 M and 1.910 M (b) 1.910 M and 0.955 M (c) 1.90 M and 1.910 M (d) 0.477 M and 0.477 M (2010) 42. 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be (a) 3 mol (b) 4 mol (c) 1 mol (d) 2 mol (2009) 43. How many moles of lead(II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g HCl? (a) 0.011 (b) 0.029 (c) 0.044 (d) 0.333 (2008) 44. The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (a) 270 kg (b) 540 kg (c) 90 kg (d) 180 kg (Atomic mass : Al = 27) (2005) 45. Molarity of liquid HCl, if density of solution is 1.17 g/cc is (a) 36.5 (b) 18.25 (c) 32.05 (d) 42.10 (2001) 46. Volume of CO 2 obtained by the complete decomposition of 9.85 g of BaCO 3 is (a) 2.24 L (b) 1.12 L (c) 0.84 L (d) 0.56 L (2000) 4 NEET-AIPMT Chapterwise Topicwise Solutions Chemistry 47. In the reaction, 4NH 3(g) + 5O 2(g) ? 4NO (g) + 6H 2 O (l) when 1 mole of ammonia and 1 mole of O 2 are made to react to completion (a) all the oxygen will be consumed (b) 1.0 mole of NO will be produced (c) 1.0 mole of H 2 O is produced (d) all the ammonia will be consumed. (1998) 48. The amount of zinc required to produce 224 mL of H 2 at STP on treatment with dilute H 2 SO 4 will be (a) 65 g (b) 0.065 g (c) 0.65 g (d) 6.5 g (1996) 49. At STP the density of CCl 4 vapour in g/L will be nearest to (a) 6.87 (b) 3.42 (c) 10.26 (d) 4.57 (1988) ANSWER KEY 1. (b) 2. (d) 3. (c) 4. (a) 5. (b) 6. (c) 7. (c) 8. (d) 9. (a) 10. (d) 11. (a) 12. (a) 13. (a) 14. (c) 15. (d) 16. (c) 17. (b) 18. (a) 19. (b) 20. (a) 21. (d) 22. (a) 23. (a) 24. (c) 25. (b) 26. (a) 27. (a) 28. (d) 29. (c) 30. (a) 31. (c) 32. (d) 33. (c) 34. (c) 35. (b) 36. (c) 37. (a) 38. (a) 39. (d) 40. (b) 41. (b) 42. (b) 43. (b) 44. (c) 45. (c) 46. (b) 47. (a) 48. (c) 49. (a) 1. (b) : Pressure= Force Area Therefore, dimensions of pressure = - MLT L 2 2 = ML –1 T –2 and dimensions of energy per unit volume = = = - -- Energy Volume ML T L ML T 3 22 12 2. (d) : Zeros placed left to the number are never significant, therefore the no. of significant figures for the numbers 161 cm, 0.161 cm and 0.0161 cm are same, i.e., 3. 3. (c) : According to Avogadro’s hypothesis, ratio of the volumes of gases will be equal to the ratio of their no. of moles. So no. of moles = Mass Mol. mass , n w n w n w H O CH 2 2 4 2 32 16 = = = ; ; So, the ratio is or ww w 23216 1612 : : :: . 4. (a) : C 3 H 8 + 5O 2 3CO 2 + 4H 2 O 1 vol. 5 vol. 3 vol. 4 vol. According to the above equation, 1 vol. or 1 litre of propane requires 5 vol. or 5 litres of O 2 to burn completely. 5. (b) : Weight of gas = 0.24 g, Volume of gas = 45 mL = 0.045 litre and density of H 2 = 0.089 g/L Weight of 45 mL of H 2 = density × volume = 0.089 × 0.045 = 4.005 × 10 –3 g Therefore, vapour density = Weight of certain volume of substance Weight of same volume e of hydrogen = × = - 024 4 005 10 59 93 3 . . . 6. (c) : If 1 L of one gas contains N molecules, 2 L of any gas under the same conditions will contain 2N molecules. 7. (c) : C 2 H 4 + 3O 2 ? 2CO 2 + 2H 2 O 28 g 96 g For complete combustion, 2.8 kg of C 2 H 4 requires =× × 96 28 28 10 3 . g = 9.6 × 10 3 g = 9.6 kg of O 2 8. (d) : Average isotopic mass of X = ×+ ×+ × ++ 200 90 1998 202 2 9082 = ++ = ˜ 18000 1592 404 100 199 96 . amu 200 amu 9. (a) : A verage atomic mass = ×+× = 19 10 81 11 100 10 81 . 10. (d) : 1 mole of substance = N A atoms 108 g of Ag = N A atoms ? = 1gof Ag atoms N A 108 24 g of Mg = N A atoms ? = 1gof Mg atoms N A 24 32 g of O 2 = N A molecules = 2 N A atoms ? = 1gof O atoms 2 N A 16 Hints & Explanations 5 Some Basic Concepts of Chemistry 7 g of Li = N A atoms ? = 1gof Li atoms N A 7 Therefore, 1 g of Li (s) , has maximum number of atoms. 11. (a) : (a) Mass of water = V × d = 18 × 1 = 18 g Molecules of water = mole × N A = = 18 18 NN AA (b) Molecules of water = mole × N A = 018 18 . N A = 10 –2 N A (c) Moles of water = = - 0 00224 22 4 10 4 . . Molecules of water = mole × N A = 10 –4 N A (d) Molecules of water = mole × N A = 10 –3 N A 12. (a) : Let atomic weight of element X is x and that of element Y is y. For XY 2 , n w = Mol.wt. 01 10 2 . = + xy ? x + 2y = 10 01 100 . = ...(i) For X 3 Y 2 , n w = Mol.wt. 005 9 32 . = + xy ?+ == 32 9 005 180 xy . ...(ii) On solving equations (i) and (ii), we get x = 40 40 + 2y = 100 ? 2y = 60 ? y = 30 13. (a) : Mass of 1 mol (6.022 × 10 23 atoms) of carbon = 12 g If Avogadro number is changed to 6.022 × 10 20 atoms then mass of 1 mol of carbon = × × × =× - 12 6 022 10 6 022 10 12 10 20 23 3 . . g 14. (c) : 1.8 gram of water = × × 6 023 10 18 18 23 . . = 6.023 × 10 22 molecules 18 gram of water = 6.023 × 10 23 molecules 18 moles of water = 18 × 6.023 × 10 23 molecules 15. (d) : Number of moles of H 2 = 1/2 Number of moles of O 2 = 4 32 Hence, molar ratio= = 1 2 4 32 41 : : 16. (c) : 8 g H 2 has 4 moles while the others has 1 mole each. 17. (b) : No. of atoms = N A × No. of moles × 3 = 6.023 × 10 23 × 0.1 × 3 = 1.806 × 10 23 18. (a) : At STP , 22.4 L = 6.023 × 10 23 molecules 15 L H 2 = ×× = × 6 023 10 15 22 4 4 033 10 23 23 . . . molecules 5 L N 2 = ×× = × 6 023 10 5 22 4 1 344 10 23 23 . . . molecules 2 g H 2 = 6.023 × 10 23 molecules 0.5 g H 2 = ×× = × 6 023 10 05 2 1 505 10 23 23 . . . molecules 32 g O 2 = 6.023 × 10 23 molecules 10 g of O 2 = ×× = × 6 023 10 10 32 1 882 10 23 23 . . molecules 19. (b) : Number of molecules = moles × N A Molecules of N 2 = 7 14 N A = 0.5 N A Molecules of H 2 = N A Molecules of NO 2 = 16 46 N A = 0.35 N A Molecules of O 2 = 16 32 N A = 0.5 N A \ 2 g H 2 (1 mole H 2 ) contains maximum molecules. 20. (a) : Specific volume (vol. of 1 g) of cylindrical virus particle = 6.02 × 10 –2 cc/g Radius of virus, r = 7 Å = 7 × 10 –8 cm Volume of virus = pr 2 l =× × × × - - 22 7 710 1010 82 8 ( ) = 154 × 10 –23 cc wt. of one virus particle = Volume (cc) Specific volume(cc/g) = × × - - 154 10 60210 23 2 . g \ Molecular wt. of virus = wt. of N A particles = × × ×× - - 154 10 60210 60210 23 2 23 . . g/mol = 15400 g/mol = 15.4 kg/mol 21. (d) : 17 g of NH 3 = 4N A atoms 4.25 g of NH 3 = × 4 17 425 N A .atoms = N A atoms = 6 × 10 23 atoms 22. (a) : Quantity of iron in one molecule = 67200 100 × 0.334 = 224.45 amu No. of iron atoms in one molecule of haemoglobin = = 224 45 56 4 . 23. (a) : Volume of oxygen in one litre of air =× = 21 100 mL 1000 210 Therefore, no. of moles = 210 22400 = 0.0093 molRead More

Offer running on EduRev: __Apply code STAYHOME200__ to get INR 200 off on our premium plan EduRev Infinity!