Stoichiometry (chemistry)

Stoichiometry (Chemistry) (Assignment – 1) 1. 2. 3. 4. 5. 6. 7. 8. 9.

A compound has the molecular formula X4O6. If 10 g of X4O6 has 5.72 g X, atomic mass of X is: (a) 32 amu (b) 37 amu (c) 42 amu (d) 98 amu Number of ions present in 2.0 litre of a solution of 0.8 M K4[Fe(CN)6] is: (a) 4.8 × 1022 (b) 4.8 × 1024 (c) 9.6 × 1024 (d) 9.6 × 1022 The molality of 1 litre solution with X% by weight H2SO4 is equal to 9. The weight of the solvent present in the solution is 910 g. The value of X: (a) 90 (b) 80.3 (c) 40.13 (d) 9 The pair of species having same percentage of carbon is: (a) CH3COOH and C6H12O6 (b) CH3COOH and C2H5OH (c) HCOOCH3 and C12H22O11 (d) C6H12O6 and C12H22O11 The isotopic abundance of C-12 and C-14 is 98% and 2% respectively. What would be the number of C-14 isotope in 12 g carbon sample: (a) 1.032 × 1022 (b) 3.01 × 1023 (c) 5.88 × 1023 (d) 6.02 × 1023 Rakesh needs 1.71 g of sugar (C12H22O11) to sweeten his tea. What would be the number of carbon atoms present in his tea: (a) 3.6 × 1022 (b) 7.2 × 1021 (c) 0.05 × 1023 (d) 6.6 × 1022 The total number of AlF3 molecule in a sample of AlF3 containing 3.01 × 1023 ions of F– is: (a) 9.0 × 1024 (b) 3.0 × 1024 (c) 7.5 × 1023 (d) 1023 3 The volume occupied by one molecule of water (density 1 g/cm ) is: (a) 18 cm3 (b) 22400 cm3 (c) 6.023 × 10–23 cm3 (d) 3.0 × 10–23 cm3 The mole fraction of water in 20% (wt./wt.) aqueous solution of H2O2 is: (a)

10. 11. 12. 13. 14. 15. 16. 17.

77 68

(b)

68 77

(c)

20 80

(d)

80 20

Which is heaviest: (a) 25 g of Hg (b) 2 moles of H2O (c) 2 moles of CO2 (d) 4 g-atom of O Total mass of neutrons in 7 mg of 14C is: (a) 3 × 1020 kg (b) 4 × 10–6 kg (c) 5 × 10–7 kg (d) 4 × 10–7 kg The number of atoms in 4.25 g NH3 is approximately: (a) 1 × 1023 (b) 1.5 × 1023 (c) 2 × 1023 (d) 6 × 1023 Amount of oxygen in 32.2 g of Na2SO4.10H2O is: (a) 20.8 g (b) 24.71 g (c) 2.24 g (d) 2.08 g Mole fraction of I2 in C6H6 is 0.2. The molality of I2 in C6H6 is: (a) 3.2 (b) 6.40 (c) 1.6 (d) 2.30 Equal masses of O2, H2 and CH4 are taken in a container. The respective mole ratio of these gases in container is: (a) 1 : 16 : 2 (b) 16 : 1 : 2 (c) 1 : 2 : 16 (d) 16 : 2 : 1 The mole fraction of the solute in one molal aqueous solution is: (a) 0.009 (b) 0.018 (c) 0.027 (d) 0.036 In the solubility of liquid solutions: (a) The solubility of a solute always increases with increasing temperature (b) There is no noticeable temperature changes

18. 19. 20. 21. 22. 23. 24.

25. 26. 27. 28. 29. 30.

31. 32. 33.

(c) A positive enthalpy of solutions is when the system gains thermal energy on becoming saturated at the fixed temperature (d) A positive heat of solution means heat is absorbed as the solute dissolves to form the saturated solution Chlorophyll, a green colouring matter contains 2.68% Mg. The number of atoms of Mg present in 1 g chlorophyll are: (a) 6.72 × 1020 (b) 6.72 × 1021 (c) 6.72 × 1022 (d) 6.72 × 1023 16 g of SOx occupies 5.6 litre at STP. Assuming ideal gas nature, the value of x is: (a) 1 (b) 2 (c) 3 (d) None of these The radius of a water molecule having density 1.0 g mL–1 is: (a) 1.925 Å (b) 73.46 Å (c) 19.25 Å (d) 7.346 Å 1.0 g of pure calcium carbonate was found to require 50 mL of dilute HCl for complete reactions. The strength of the HCl solution is given by: (a) 4 N (b) 2 N (c) 0.4 N (d) 0.2 N 100 mL each of 0.5 N NaOH, N/5 HCl and N/10 H2SO4 are mixed together. The resulting solution will be: (a) Acidic (b) Neutral (c) Alkaline (d) None of these 25 mL of 3.0 M HNO3 are mixed with 75 mL of 4.0 M HNO3. If the volumes are additive, the molarity of the final mixture would be: (a) 3.25 M (b) 4.0 M (c) 3.75 M (d) 3.50 M 0.7 g of Na2CO3.xH2O were dissolved in water and the volume was made to 100 mL, 20 mL of this solution required 19.8 mL of N/10 HCl for complete neutralization. The value of x is: (a) 7 (b) 3 (c) 2 (d) 5 Equivalent wt. of an acid salt NaHSO4 is: (a) M/1 (b) M/2 (c) M/3 (d) None of these When a metal is burnt, its weight is increased by 24%. The equivalent weight of the metal will be: (a) 25 (b) 24 (c) 33.3 (d) 76 100 mL of a mixture of NaOH and Na2SO4 is neturalised by 10 mL of 0.5 M H2SO4. Hence NaOH in 100 mL solution is : (a) 0.2 g (b) 0.4 g (c) 0.6 g (d) None of these The amount of H2SO4 present in 1200 mL of 0.2 N solution is: (a) 11.76 g (b) 12.76 g (c) 13.76 g (d) 23.52 g How many millilitre of 0.5 M H2SO4 are needed to dissolve 0.5 g of copper (II) carbonate: (a) 8.10 mL (b) 16.20 mL (c) 4.05 mL (d) 12.05 mL 0.63 g of diabasic acid was dissolved in water. The volume of the solution was made 100 mL. 20 mL of this acid solution required 10 mL of N/5 NaOH solution. The molecular mass of acid is: (a) 63 (b) 126 (c) 252 (d) 128 Number of positive ions in 1.45 mole of K2SO4are: (a) 1.75 × 1024 (b) 8.73 × 1023 (c) 8.73 × 1024 (d) 1.75 × 1023 Equal moles of H2O and NaCl are present in a solution. The molality of NaCl solution is: (a) 55.6 (b) 5.56 (c) 1 (d) 0.5 22 The mass of 1 × 10 molecules of CuSO4.5H2O is:

34. 35. 36. 37. 38. 39.

(a) 4.144 g (b) 5.144 g (c) 6.144 g (d) None of these Weight of one atom of an element is 6.644 × 10–23 g. The g-atoms of element in 40 kg is: (a) 102 (b) 103 (c) 104 (d) 105 A compound contains 10–2% of phosphorus. If atomic mass of phosphorus is 31, the molar mass of the compound having one phosphorus atom per molecule is: (a) 31 (b) 31 × 102 (c) 31 × 104 (d) 31 × 103 Total number of electrons present in 11.2 litre of NH3 at STP are: (a) 6.02 × 1023 (b) 3.01 × 1023 (c) 3.01 × 1024 (d) 5.1 × 1024 Al2(SO4)3.XH2O has 8.1% aluminium by mass. The value of X is: (a) 4 (b) 10 (c) 16 (d) 18 Total number of atoms present in 1.0 cm3 of solid urea (density 0.3 g/cm3) at 25°C are: (a) 3.01 × 1021 (b) 2.41 × 1022 (c) 3.01 × 1022 (d) 2.41 × 1023 –1 The density of liquid (mol. wt. = 70) is 1.2 g mL . If 2 mL of liquid contains 35 drops, the number of molecules of liquid in one drop are: (a)

40.

1.2 NA 35

(b)

1 NA 35

(c)

1.2 NA 352

(d) 1.2 N A

The atomic weight of a triatomic gas is a. The correct formula for the number of moles of gas in its w g is: (a)

3w a

(b)

w 3a

(c) 3wa

(d)

a 3w

Stoichiometry (Chemistry) (Assignment – 1)

Answer Key 1. A

2. B

3. B

4. A

5. A

6. A

7. D

8. D

9. B

10. C

11. B

12. D

13. B

14. A

15. A

16. B

17. C

18. A

19. B

20. A

21. C

22. C

23. C

24. C

25. A

26. C

27. B

28. A

29. A

30. B

31. A

32. A

33. A

34. B

35. C

36. C

37. D

38. B

39. C

40. B