Concept Of Mole MCQs
Question 1. 1 mole is the number of atoms in exactly
(1) 1g of 12C
(2) 12 g of 12C
(3) 1/12 g of 12C
(4) None of these
Answer: (2) 12 g of 12C
Question 2. The mass of a C-12 atom is
(1) 12g
(2) 1/12 g
(3) 12/ NA g
(4) 12 × NA g
Answer: (3) 12/ NA g
Question 3. The number of moles (n), the number of particles (N) and the Avogadro number (NA) are related as
(1) n =NA/N
(2) N/NA=N
(3) n = N/NA
(4) n = N.NA
Answer: (3) n = N/NA
Question 4. 16 g of oxygen is the mass of oxygen of
(1) One oxygen atom
(2) One oxygen molecule
(3) 1-mole oxygen molecule
(4) One-mole oxygen atom
Answer: (4) One-mole oxygen atom
Question 5. 6.4 g of oxygen is equivalent to
(1) 0.4 mol of oxygen atoms
(2) 0.4 mol of oxygen molecules.
(3) 0.2 mol of oxygen atoms
(4) None of these
Answer. (1) 0.4 mol of oxygen atoms
Question 6. 0.10 mol of carbon is equivalent to
(1) 1.2 g of carbon
(2) 1/12 g of carbon
(3) 12.0 g of carbon
(4) 0.1 g of carbon
Answer:(1) 1.2 g of carbon
Question 7. A sample is known to contain 2 x 6.022 x 1023. hydrogen atoms. How many mol hydrogen atoms does it contain?
(1) 1 mol
(2) 1/2 mol
(3) 2 mol
(4) NA mol
Answer: (3) 2 mol
Question 8. Formula mass of water (H2O) is
(1) 33
(2) 17
(3) 10
(4) 18
Answer: (4) 18
Question 9. Consider two gases A and B or ideal gas with MA > MB. The molar volumes (Vm) at given pressure and temperature are like
(1) Vm(A)= Vm(B)
(2) Vm(A)> Vm(B)
(3)Vm(A) <Vm(B)
(4) No relation
Answer: (1) Vm(A)= Vm(B)
Question 10.A sample contains m g of a compound X (mx = molar mass). The sample contains n mol of X. Then n, m and M are related as
(1) M=m.n
(2) M= n/n
(3) M= n/m
(4) n=m.M
Answer: (2) M = m/n
Question 11. ‘Mole’ means
(1) A molecule
(2) Number of molecules
(3) Number of atoms
(4) Avogadro’s number of any particle
Answer: (4) Avogadro’s number of any particle
Question 12. 0.012 kg of C-12isotope contains how many C-12atoms ?
(1) 12
(2) 6.022 x1023
(3) 1.66 x10-24 g
(4) 12 g atom .
Answer: (2) 6.022 x1023
Question 13. Avogadro’s number is used in
(1) Chemistry only
(2) Physics only
(3) Biology only
(4) Chemistry, physics and biology
Answer: (4) Chemistry, physics and biology
Question 14. Unit of relative atomic mass is
(1) Gram
(2) Kilogram
(3) a.m.u.
(4) No unit
Answer: (4) No unit
Question 15. Which scientist first gave the concept of molecule?
(1) Dalton
(2) Avogadro
(3) Berzilius
(4) Boyle
Answer: (2) Avogadro
Question 16. What is the volume of 1 gram-molecule of a gas or vapour at NTP?
(1) 22.4 ml
(2) 22.4 lit
(3) 1000 ml
(4) 2.24 lit
Answer: (2) 22.4 lit
Question 17. In the reaction, N2+3H2=2NH3 the ratio of volumes of nitrogen, hydrogen, and ammonia is 1 : 3: 2. These figures illustrate the law of
(1) Constant proportion
(2) Multiple proportion
(3) Reciprocal proportion
(4) Gay Lussac’s law of gaseous volumes
Answer: (4) Gay Lussac’s law of gaseous volumes
Question 18. At NTP, 5.6 lit of a gas weighs 8 grams. The vapour density of the gas is
(1) 32
(2) 40
(3) 16
(4) 8
Answer: (3) 16
Question 19. Which of the following contains the least number of molecules?
(1) 19 H2
(2) 2g N2
(3) 4g O2
(4) 11g CO2
Answer: (2) 2g N2
Question 20. Which of ‘the following volumes of the gas at NTP contains the largest number of molecules?
(1) 200 ml H2
(2) 100 ml O2
(3) 150 ml N2
(4) 22.5 ml NH3
Answer: (1) 200 ml H2,
Question 21. Which one of the following statements is not applicable to 1 mole of carbon dioxide?
(1) 22 g CO2
(2) 22.4 lit of the gas
(3) 1 gram atom of carbon and 2 gram atoms of oxygen
(4) 6.023 x 1023 molecules of carbon dioxide
Answer: (1) 22 g CO2
Question 22. A mole of any gas
(1) Always occupies one liter
(2) Always occupies 22.4 lit at NTP
(3) Can occupy any volume at NTP
(4) Always occupies 11.2 lit at NTP
Answer: (2) Always occupies 22.4 lit at NTP
Question 23. The latest standard of atomic weight is
(1) Hydrogen = 1
(2) Oxygen = 16
(3) Carbon = 12
(4) Nitrogen = 14
Answer: (3) Carbon = 12
Question 24. The approximate number of molecules in 4.25 g of ammonia is
(1) 1.0 x 1023
(2) 1.5 x 1023
(3) 2.0 x 1023
(4) 3.5 x 1023
Answer: (2) 1.5 x 1023
Question 25. Atomic weight of chlorine is 35.5. It has two isotopes of atomic weights 35 and 37. What is the percentage of the heavier isotope in the sample?
(1) 5
(2) 25
(3) 20
(4) 15
Answer: (2) 25
Question 26 Number of molecules in one litre of water is close to
(1)\(\frac{6.023}{23.4} \times 10^{23}\)
(2) 18 x 6.023 x 1023
(3) \(\frac{18}{22.4} \times 10^{23}\)
(4) 55.5 x 6.023 x 1023
Answer: (4) 55.5 x 6.023 x 1023
Question 27. Volume at NTP of 0.22 g of CO2 is the same as that of
(1) 0.01 g of H2
(2) 0.085 g of NH3
(3) 320 mg of gaseous SO2
(4) All of the above
Answer: (4) All of the above
Question 28. Avogadro’s number of helium atoms weighs
(1) 1 g
(2) 4 g
(3) 8 g
(4) 4 x 6.025 x1023 g
Answer: (2) 4 g
Question 29. The molecular mass of CO2 is 44 a.m.u. Biotec? s number is 6.023 x 1023, therefore, the mass of one molecule of CO2 , is
(1) 7.31 x 10-23
(2) 3.65 x 10-23
(3) 1.01 x 10-23
(4) 2.01 x 10-23
Answer: (1) 7.31 x 10-23
Question 30. 4.0 grams of caustic soda contain
(1) 6.023 x 1023 atoms of hydrogen
(2) 4 g atoms of sodium
(3) 6.023 x 1022atoms of sodium
(4) 4 moles of caustic soda
Answer: (3) 6.023 x 1022 atoms of sodium:
Question 31. Which of the following weighs the least?
(1) 24 g of magnesium
(2) 0.9 moles of nitric oxide
(3) 22.4 lit of N2
(4) 6.023 x 1024 molecules of oxygen
Answer: (1) 24 g of magnesium
Question 32. One mole of CO2 contains
(1) 6.023 x 1023 atoms of carbon
(2) 6.023 x 1023 atoms of oxygen
(3) 18.1 x 1023 molecules of carbon dioxide
(4) 3 gram atoms of carbon dioxide
Answer: (1) 6.023 x 1023 atoms of carbon
Question 33. One a.m.u. is
(1) 1.00748 g
(2) 0.000549 g
(3) 1.66 x.10-24 g
(4) 6.023 x 10-23 g
Answer: (3) 1.66 x 10-24g
Question 34. The vapour density of a gas is 11.2. The volume occupied by 11.2 g of the gas at NTP is
(1) 1 L
(2) 11.2 L
(3) 22.4 L
(4) 10 L
Answer: (2) 11.2 L
Question 35. The vapour density of pure ozone would be
(1) 16
(2) 24
(3) 32
(4) 48
Answer: (2) 24
Question 36. At STP 5.6 lit of a gas weights 60 g. The vapour density of the gas is.
(1) 30
(2) 60
(3) 120
(4) 240
Answer: (3) 120
Question 37. The largest number of molecules is in
(1) 34 g water
(2) 54 g of CO2
(3) 46 g of CH3OH
(4) 54 g of N2 O5
Answer : (1) 34 g water
Question 38. The number of oxygen atoms in 4.4 g of CO, is approximately
(1) 1.2 x 1023
(2) 6 x 1023
(3) 6 x1022
(4) 12 x 1023
Answer: (1) 1.2 x 10
Question 39. The number of molecules in 16 g of methane (CH,) is
(1) 3.0 x 1023
(2) 6.023 x 1023
(3) \(\frac{16}{6.023} \times 10^{23}\)
(4) \(\frac{16}{3} \times 10^{23}\)
Answer. (2) 6.023 x 1023
Question 40. If 0.56 g of a gas occupies 280 ml at NTP, then its molecular mass is
(1) 4.8
(2) 44.8
(3) 2
(4) 22.4
Answer: (2) 44.8
