Free NEET Chemistry multiple-choice questions on Mole Concept & Molar Mass. Attempt each question and reveal the answer with a full explanation.
Which of the following has the maximum number of atoms? 1 g of Li(s) ( At. mass = 7 ) 1 g of Ag(s) ( At. mass = 108 ) 1 g of Mg(s) ( At. mass = 24 ) 1 g of O 2(g) ( At. mass = 16 ) Which among the following contains the maximum number of molecules? 2 g H 2 16 g O 2 28 g N 2 44 g CO 2 If we consider that 1/6 in place of 1/12 mass of Carbon atom is taken as the relative atomic mass unit ( u ), the mass of one mole of a substance will: decrease by half increase two-fold remain unchanged increase by 1/12th Which of the following contains the same number of atoms as 12 g of Magnesium? (At. mass: Mg=24, C=12, Ca=40 ) 20 g of Calcium 12 g of Carbon 24 g of Magnesium 6 g of Carbon A measured temperature on Fahrenheit scale is 200 o F . What will this reading be on Celsius scale? 93.3 o C 40 o C 112.4 o C 84.2 o C The number of molecules in 8.96 L of a gas at 0 o C and 1 atm pressure is: 0.4 N A 0.2 N A 0.5 N A 0.8 N A The number of water molecules is maximum in: 18 mL of water 1.8 g of water 18 g of water 10 -3 mol of water Out of 1.0 g H 2 , 1.0 g O 2 and 1.0 g F 2 , which contains the largest number of molecules? 1.0 g of H 2 1.0 g of O 2 1.0 g of F 2 All contain equal molecules The molarity of pure water is: 55.5 M 100 M 18 M 1 M The mass of 0.5 moles of N 2 gas is: 14 g 28 g 7 g 0.5 g Which of the following is defined as the mass of substance containing the same number of fundamental units as there are atoms in exactly 12.000 g of 12 C ? Mole Atomic mass unit Molar mass Equivalent weight The prefix 'femto' stands for: 10 -15 10 -12 10 -9 10 -18 The prefix 'nano' stands for: 10 -9 10 -6 10 -12 10 -15 Total number of atoms in 44 g of CO 2 is: 3 N A 1 N A 2 N A 44 N A The number of molecules in 16 g of methane ( CH 4 ) is: 6.022 10 23 3.011 10 23 1.204 10 24 6.022 10 22 What is the weight of 1 atom of Hydrogen in grams? 1.66 10 -24 g 1.66 10 -27 g 6.022 10 23 g 1.008 g What is the volume occupied by 0.25 moles of any ideal gas at STP? 5.6 L 11.2 L 22.4 L 2.24 L One mole of fluorine molecules ( F 2 ) contains: 1.2044 10 24 atoms of F 6.022 10 23 atoms of F 1 g of F 22.4 L of F 2 at any temperature The SI unit of 'amount of substance' is defined as the amount containing as many elementary entities as there are atoms in exactly: 0.012 kg of 12 C 12 g of C (natural mixture) 1 g of H 0.016 kg of 16 O The mass of one atom of oxygen ( O-16 ) is approximately: 2.66 10 -23 g 1.66 10 -24 g 16 g 1.06 10 -22 g The number of atoms in 0.1 mol of a triatomic gas is: 1.806 10 23 6.022 10 22 3.606 10 23 1.806 10 22 A mixture of 2 moles of helium and 4 moles of nitrogen is present in a vessel. The mole fraction of nitrogen in the mixture is: 0.67 0.33 0.50 2.0 The prefix 'pico' corresponds to which of the following multiples? 10 -12 10 -9 10 -15 10 -6 What mass of Magnesium (Atomic mass = 24 ) contains the same number of atoms as 32 g of Sulfur (Atomic mass = 32 )? 24 g 12 g 48 g 32 g How many moles of HCl are present in 250 mL of a 0.5 M solution? 0.125 mol 0.5 mol 0.25 mol 1.25 mol The volume of 0.1 mole of an ideal gas at 273 K and 1 atm pressure is: 2.24 L 22.4 L 1.12 L 0.224 L Which concentration term is independent of temperature? Molality Molarity Normality Formality What mass of Mg (at. wt. 24 ) will provide the same number of atoms as are present in 12 g of Carbon? 24 g 12 g 48 g 6 g How many molecules are present in one gram-molecular mass of any substance? 6.022 10 23 3.011 10 23 1.204 10 24 10 23 Which of the following represents the largest number of particles? 1 mole of H 2 1 mole of He 1 mole of O 2 All have the same number of particles Which of the following is not a base unit in the SI system? Gram Mole Candela Kelvin The unit of molarity is: mol/L mol/kg g/L mol/m 3 One 'gram-atom' of Nitrogen represents: 14 g of Nitrogen 28 g of Nitrogen 1 g of Nitrogen 6.022 x 10 23 molecules of Nitrogen The prefix 'atto' corresponds to the multiplier: 10 -18 10 -15 10 -21 10 -12 The unit of molality is: mol/kg mol/L g/L unitless What is the mass of 1 atom of Gold ( Au , atomic mass = 197 u ) in grams? 3.27 10 -22 g 1.97 10 -23 g 3.27 10 -25 g 1.66 10 -24 g 6.02 10 20 molecules of urea are present in 100 mL of its solution. The concentration of solution is 0.02 M 0.01 M 0.001 M 0.1 M Equal masses of H2 , O2 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 H2 : O2 : methane would be :- 8 : 16 : 1 16 : 8 : 1 16 : 1 : 2 8 : 1 : 2 Match the polymer in Column-I to the monomer from Column-II and assign the correct code. Code: (a) (b) (c) (d) array ll Column-I & Column-II (a) Nylon-6 & (i) ethylene glycol, terephthallic acid (b) Dacron & (ii) urea, formaldehyde (c) Glyptal & (iii) ethylene glycol, phthallic acid (d) Novolac & (iv) Phenol, formaldehyde ; & (v) Caprolactum array a-v, b-iii, c-i, d-ii a-v, b-i, c-iii, d-iv a-iii, b-i, c-iv, d-ii a-ii, b-v, c-iii, d-iv In which case is number of molecules of water maximum? 0.00224 L of water vapours at 1 atm and 273 K 0.18 g of water 18 mL of water 10 -3 mol of water Which one of the followings has maximum number of atoms ? 1 g of Mg(s) [Atomic mass of Mg = 24] 1 g of O2 (g) [Atomic mass of O = 16] 1 g of Li(s) [Atomic mass of Li = 7] 1 g of Ag(s) [Atomic mass of Ag = 108] The highest number of helium atoms is in 4 mol of helium 4 u of helium 4 g of helium 2.271098 L of helium at STP The number of hydrogen atoms present in 5.4 g of urea is: (Given: Molar mass of urea : 60 g mol -1 , N A : 6.022 10 23 particles mol -1 ) 2.168 10 22 2.168 10 23 1.084 10 22 1.084 10 23 If Avogadro number N A , is changed from 6.022 10 23 mol -1 to 6.022 10 20 mol -1 , this would change: the mass of one mole of carbon the ratio of chemical species to each other in a balanced equation the ratio of elements to each other in a compound the definition of mass in units of grams Equal masses of H 2 , O 2 and methane ( CH 4 ) 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:CH 4 would be: 16:1:2 8:1:2 16:8:1 1:2:16 Which of the following contains the same number of molecules as 1 g of Nitrogen gas ( N 2 )? 1 g of Carbon Monoxide ( CO ) 1 g of O 2 1 g of CH 4 1 g of CO 2 Calculate the mass of C-12 atom in grams. 1.99 10 -23 g 6.022 10 -23 g 1.66 10 -24 g 12 g The maximum number of molecules are present in: 15 L of H 2 gas at STP 5 L of N 2 gas at STP 0.5 g of H 2 gas 10 g of O 2 gas What is the mass of one atom of Calcium (Atomic mass = 40 u ) in grams? 6.64 10 -23 g 40 g 1.66 10 -24 g 6.022 10 -23 g A gas is found to have a vapour density of 11.2 at STP. What is the volume occupied by 11.2 g of this gas at STP? 11.2 L 22.4 L 5.6 L 44.8 L The number of atoms in 4.25 g of NH 3 is approximately: 6.022 10 23 1.5 10 23 2.4 10 24 3.011 10 23 Which of the following contains the same number of molecules as 16 g of oxygen ( O 2 )? 14 g of N 2 16 g of O 3 28 g of CO 2 1 g of H 2 If the concentration of glucose ( C 6H 12 O 6 ) in blood is 0.9 g/L , what is its molarity? 0.005 M 0.05 M 5.0 M 0.9 M The number of significant figures in the result of 2.5 + 3.45 + 4.123 is: 3 2 4 1 If 1 mL of water contains 20 drops, the number of molecules in one drop of water is: (Density of water = 1 g/mL ) 1.67 10 21 6.022 10 23 1.34 10 22 4.34 10 20 What is the mass of one molecule of yellow phosphorus ( P 4 )? (Atomic mass of P = 31 ) 2.05 10 -22 g 1.24 10 -22 g 5.15 10 -23 g 1.02 10 -22 g The mass of 1.2044 10 23 molecules of CO 2 is: 8.8 g 4.4 g 44 g 0.88 g Which of the following contains the same number of molecules as 4.4 g of CO 2 ? 2.8 g of CO 4.4 g of N 2O 3.2 g of O 2 2.8 g of N 2 One mole of CO 2 contains: 6.022 10 23 atoms of Oxygen 18.1 10 23 molecules of CO 2 3 g-atoms of CO 2 6.022 10 23 atoms of Carbon The total number of electrons in 1.6 g of methane ( CH 4 ) is: 6.022 10 23 6.022 10 24 1.6 10 23 10 6.022 10 23 The ratio of the number of atoms in 4 g of Hydrogen to 16 g of Magnesium is: 6:1 3:1 1:1 4:1 What is the mass of 1 10 22 molecules of CuSO 4 5H 2O ? (Molar mass = 249.5 g/mol ) 4.14 g 0.414 g 41.4 g 2.49 g The number of atoms in 0.004 g of magnesium is closest to: 10 20 10 17 10 23 10 19 In which case is the number of molecules of water maximum? 18 mL of water 0.18 g of water 0.00224 L of water vapours at 1 atm and 273 K 10 -3 mol of water Which of the following contains the maximum number of atoms? 1 g of Li(s) [At. wt = 7] 1 g of Ag(s) [At. wt = 108] 1 g of Mg(s) [At. wt = 24] 1 g of O 2(g) [At. wt = 16] Which of the following has the same number of atoms as 16 g of oxygen ( O 2 )? 4 g of H 2 16 g of O 3 28 g of N 2 14 g of N 2 According to the rules of significant figures, when 6.345 and 6.335 are rounded off to three significant figures, the results are respectively: 6.34 and 6.34 6.35 and 6.33 6.34 and 6.33 6.35 and 6.34 Which of the following contains the same number of atoms as 32 g of Sulfur? 40 g of Calcium 12 g of Carbon 8 g of Oxygen 2 g of Hydrogen The total number of Na + ions in 100 mL of 0.1 M Na 2SO 4 solution is: 1.2044 10 22 6.022 10 22 1.2044 10 23 6.022 10 21 The molarity of a 0.3 N solution of H 3PO 4 (phosphoric acid) is: 0.1 M 0.3 M 0.9 M 0.6 M The number of gas molecules per 1 cm 3 at STP is known as: Loschmidt number Avogadro number Boltzmann constant Faraday constant Two vessels of the same volume contain O 2 and O 3 respectively at the same temperature and pressure. The ratio of the number of atoms in the two vessels is: 2:3 1:1 3:2 4:3 According to the rules of significant figures, the result of 12.11 + 18.0 + 1.012 should be reported as: 31.1 31.122 31.12 31 Which of the following contains the same number of molecules as 2 g of Hydrogen ( H 2 )? 28 g of N 2 16 g of O 2 14 g of N 2 2 g of He How many atoms of oxygen are there in 0.5 mole of CO 2 ? 6.022 10 23 3.011 10 23 1.204 10 24 1.806 10 24 What is the mass of nitrogen present in 0.5 mole of Urea ( NH 2CONH 2 )? 14 g 28 g 7 g 21 g The total number of neutrons in 2.0 g of Deuterium gas ( D 2 ) is: ( N A is Avogadro's number) 0.5 N A 1.0 N A 2.0 N A 4.0 N A What is the weight of one molecule of glucose ( C 6H 12 O 6 )? 2.988 x 10 -22 g 180 g 1.66 x 10 -24 g 3.0 x 10 -23 g The ratio of the mass of 1 mole of O 2 to the mass of 1 molecule of O 2 is: 6.022 10 23 32 16 1/6.022 10 23 What is the mole fraction of glucose in 10 % (w/w) glucose solution? 0.011 0.1 0.018 0.05 The Vapour Density of a gas is 11.2 . The volume occupied by 11.2 g of this gas at STP is: 11.2 L 22.4 L 5.6 L 44.8 L The total number of electrons in 1.4 g of N 3- ion is: (Given N A = 6.022 10 23 ) 1.0 N A 0.7 N A 7.0 N A 10 N A The number of significant figures in the result of the subtraction 15.450 - 15.4 is: 1 2 3 4 A gaseous mixture contains O 2 and N 2 in the ratio 1:4 by weight. The ratio of their number of molecules is: 7:32 1:4 32:7 7:8 Which of the following contains the same number of atoms as 1 g of Hydrogen gas ( H 2 )? 12 g of Magnesium 1 g of Helium 16 g of Oxygen 23 g of Sodium How many oxygen atoms are there in 4.4 g of N 2O ? 6.022 10 22 1.204 10 23 6.022 10 23 3.011 10 22 The mass of V mL of a gas at STP is W g . Its gram molecular mass is: 22400 W V V W 22400 V 22400 W 22400 V W What is the weight of 10 22 molecules of NH 3 ? 0.282 g 1.70 g 0.17 g 2.82 g Which of the following is the mass of one mole of protons? (Mass of one proton = 1.672 10 -24 g ) 1.007 g 1.000 g 1.672 g 0.001 g One mole of any gas at STP ( 273 K , 1 atm ) occupies a volume of: 22.4 L 22.7 L 24.4 L 11.2 L The number of electrons in 1.8 mL of H 2O (density = 1 g/mL ) is: 6.022 10 23 1.8 10 23 6.022 10 22 10 10 23 Volume occupied by one molecule of water (density = 1 g/cm 3 ) is: 3.0 10 -23 cm 3 6.023 10 -23 cm 3 3.0 10 -22 cm 3 9.0 10 -23 cm 3 If NaCl is doped with 10 -4 mol % of SrCl2 , the concentration of cation vacancies will be ( N A = 6.02 10 23 mol -1 ) 6.02 10 16 mol -1 6.02 10 17 mol -1 6.02 10 14 mol -1 6.02 10 15 mol -1 A metal has a fcc lattice. The edge length of the unit cell is 404 pm . The density of the metal is 2.72 g cm -3 . The molar mass of the metal is ( N A Avogadro's constant = 6.02 10 23 mol -1 ) 40 g mol -1 30 g mol -1 27 g mol -1 20 g mol -1 What fraction of one edge centred octahedral void lies in one unit cell of fcc? 1 2 1 3 1 4 1 12 Among the following, choose the ones with equal number of atoms. A. 212 g of Na2CO3(s) [molar mass = 106 g] B. 248 g of Na2O(s) [molar mass = 62 g] C. 240 g of NaOH(s) [molar mass = 40 g] D. 12 g of H2(g) [molar mass = 2 g] E. 220 g of CO2(g) [molar mass = 44 g] Choose the correct answer from the options given below : B, D, and E only A, B, and C only A, B, and D only B, C, and D only The number of valence electrons in 4.2 g of N 3- ion is: ( N A is Avogadro's number) 2.4 N A 4.2 N A 1.6 N A 3.2 N A Which of the following has the smallest mass in grams? 1 atom of nitrogen 1 molecule of H 2O 10 -10 moles of O 2 1 microgram of He Calculate the number of moles of an ideal gas present in 11.2 L at 273 C and 2 atm pressure. 0.5 mol 1.0 mol 0.25 mol 2.0 mol If the density of water is 1 g/mL , then the volume occupied by one molecule of water is approximately: 3.0 10 -23 mL 6.0 10 -23 mL 3.0 10 -22 mL 1.8 10 -23 mL