Chemistry-6.Work Book (Phase - VI)
Work Book (Phase - VI)
Subjective:
Board Type Questions
1. At 800°K, the two solutions of glucose in water of concentration 0.01 M and 0.001 M are separated by semi permeable membrane with respect to water. On which solution, pressure need to applied to prevent osmosis and how much.
2. Vapour pressure of pure benzene at certain temperature is 640 mm Hg. A non–volatile, non–electrolyte substance weighing 2.175 gm is added to 39.0 gm of benzene, the vapour pressure of solution is found to be 600 mm Hg. What is the molecular weight of the substance?
3. A storage battery contains a solution of H2SO4 38% by weight at this concentration, Vant Hoff’s factor is 2.5. At what temperature battery contents freeze.
4. If a solution of mercuric cyanide containing 3 gms per litre has an osmotic pressure of 232 mmHg at 25°C what is the appearent molecular weight and degree of dissociation of mercuric cyanide.
5. Calculate the molecular weight of cellulose acetate if its 0.5% (wt./vol) solution in acetone (sp. gr. = 0.9) shows an osmotic rise of 23 mm against pure acetone at 27°C.
6. Calculate the number (n) of atoms contained within (a) cubic cell (b) a body – centred cubic cell (c) a face – centred cubic cell.
7. A compound formed by elements A and B crystallizes in cubic structure where A atoms are at the corners of a cube and B atoms are at the face centre. What is the formula of the compound?
8. A closed packed structure of uniform spheres has the cell edge = 0.8 mm. Calculate the radius of molecule if it has
(a) single cubic lattice
(b) b.c.c lattice
(c) f.c.c lattice
9. At room temperature, sodium crystallizes in a body-centred cubic lattice with
a = 2.24 A. Calculate theoretical density of sodium (At. Wt. Of Na = 23)
10. The unit cell length for LiCl (NaCl structure) is 5.14AA. Assuming anion-anion contact, calculate the ionic radius for chloride ion.
11. A solid compound AB has NaCl structure. If the radius of the cation is 100 pm (picometer) what is the radius of anion B? 1 pm = 1012 m.
12. In a compound AB, the ionic radii of A+ and B are 88 pm and 200 pm respectively. What is the co-ordination number of A+?
13. Calculate the number of atoms in a cube based unit cell having one atom on each corner and two atoms on each diagonal.
14. Molybdenum forms body – centred cubic lattice crystal of density 12.96 g cm3. Calculate edge length of unit cell. Atomic weight of Mo = 95.94.
15. Why excess of carbon is added in zinc metallurgy? Explain.
16. Why magnesium oxide is used for the lining of steel making furnace?
17. Why chlorite roasted and not cuprite in the extraction of copper?
18. Why partial roasting of sulphide ore is done in the metallurgy of copper?
19. Zinc and not copper is used for the recovery of silver from the complex [Ag(CN)2].
20. Why lime stone is added to ore in the metallurgy of iron?
21. Identify (A) and (B) in the following reactions.
Colemanite + A Na2B4O7
Na2B4O7 + (B) H3BO3
22. When the ore haematite is burnt in air with coke around 2000C along with lime, the process not only produces steel, but also produces a silicate slag that is useful in making building material such as cement, discuss the same and show through balanced chemical equation.
23. Write the chemical reactions involved in the extraction of metallic silver from argentite.
24. What happens when?
(i) A beam of light is passed through As2S3 sol? (ii) KCl is added to Fe(OH)2 solution?
25. Frequently preparation of a colloid such as a protein can be made more stable if the colloid is dialyzed. Why is this so?
26. Name the factors on which the adsorption of a gas on a solid depends.
27. Give the expression of Freundich isotherms.
28. To which colloidal system does milk belong?
29. Define coagulation.
30. What happens when colloidal solutions of Fe(OH)3 and As2S3 are mixed?
31. What happens when an electric field is applied to a colloidal dispersion?
32. Physical and chemical adsorption respond differently to a rise in temperature. What is this difference and why is it so?
33. What is the difference between multi-molecular and macromolecular colloids? Give two examples of each type.
34. How will you distinguish between the following pairs of terms?
(i) Hexagonal close packing and cubic close packing.
(ii) Crystal lattice and unit cell.
(iii) Tetrahedral void and octahedral void.
35. What type of crystal structure is possessed by NaCl? How can you calculate the number of atoms of each of Na and Cl present per unit cell of NaCl?
36. What is the difference between ‘Schottky defects’ and ‘Frenkel defects’?
37. What are piezoelectric crystals? Give their important uses.
38. Arrange the following substances in order of increasing ability to coagulate:
(i) a negatively charged sol and (ii) a positively charged sol:
ZnSO4; AlCl3; Na3PO4
39. Answer the following:
(i) Why is lyophilic colloid comparatively more stable? (ii) Explain demulsification.
40. (a) Name two colloids which are used as protective colloids.
(b) What is the colloidal sulphur? How is it obtained?
41. Give the answer with proper reasoning:
Gold numbers for the gelatin, haemoglobin and sodium oleate are 0.005, 0.05 and 0.70 respectively. Which has the greatest protective power?’
IIT Level Questions
42. A metal crystallizes into two cubic phases, face-centred cubic (f.c.c) and body-centred cubic (b.c.c) whose unit cell lengths are 3.5 and 3.0 A, respectively. Calculate the ratio of densities of f.c.c and b.c.c.
43. Calculate the concentration of cation vacancies if NaCl is doped with 103 mole % of SrCl2.
44. A solid AB has the NaCl structure. If the radius of the cation A+ is 120 pm, calculate the maximum possible value of the radius of the anion B.
45. Tungsten has a body-centred cubic lattice and each lattice point is occupied by one atom. Calculate the radius of metallic tungsten if density of tungsten is 19.30 g cm3 and atomic weight is 183.9.
46. KF has NaCl structure. What is the distance between K+ and F in KF, if the density of KF is 2.48 g cm3?
47. If the apparent degree of ionization of KCl (KCl = 74.5 gm/mole) in water at 290°K is 0.86. Calculate the mass of KCl which must be made upto 1 litre of aq. solution to the same osmotic pressure as the 4% solution of glucose at that temperature.
48. A complex is represented as CoCl3.xNH3. Its 0.1 m solution in aqueous solution shows DTf = 0.558° Kf(H2O) = 1.86 mol–1 K and assume 100% ionization and co–ordination number of Co(III) is six . What is the complex?
49. A solution containing 6 g of a solute dissolved in 250 cm3 of water gave an osmotic pressure of 4.5 atmosphere at 27C. Calculate the boiling point of the solution. The molal elevation constant for water is 0.52C per 1000 g.
50. Write the mathematical form of Langmuir adsorption isotherm. How does Freundlich adsorption isotherm follow from it?
51. A solution of urea in water has a boiling point of 100.128C. Calculate the freezing point of the same solution. Molal constants for water Kf and Kb are 1.86C and 0.512C respectively.
Objective:
Multiple choice questions with single correct options
1. The hcp arrangement of ions is described by
(A) ABAB (B) ABABA
(C) ABCABC (D) ABCABCABC
2. Frenkel defect appears in
(A) AgI (B) ZnS
(C) AgBr (D) all
3. Lithium selenide can be described as a closet-packed array of selenide ions with lithium ions in all of the tetrahedral holes. Formula of lithium selenide is
(A) Li2Se (B) LiSe
(C) LiSe2 (D) Li3Se
4. In hcp structure, the packing fraction is
(A) 0.68 (B) 0.74
(C) 0.50 (D) 0.54
5. A group of 13 elements if added in small amount of Ge, ………….is formed
(A) n-type semiconductor (B) p-type semiconductor
(C) insulator (D) rectifier
6. How many “nearest – neighbours” does potassium atom have in bcc lattice?
(A) 8 (B) 6
(C) 4 (D) 2
7. Ferrimagnetism is in
(A) (B)
(C) (D) none
8. ZnS does not crystallize in the NaCl structure. It is due to
(A) the ratio is 0.402, too low to avoid anion-anion contact in the NaCl structure
(B) the ratio is 0.402, too high to avoid cation-cation in the NaCl structure
(C) both correct
(D) none correct
9. 8 : 8 coordination of CsCl is found to change into 6 : 6 on
(A) applying high P (B) increase in temperature
(C) both (D) none
10. An azeotropic solution of two liquids has a boiling point lower than either of them when it
(A) shows negative deviation from Raoult’s law
(B) shows positive deviation from Raoult’s law
(C) shows ideal behaviour
(D) is saturated
11. Depression of freezing point of 0.01 molal aq. CH3COOH solution is 0.02046. 1 molal urea solution freezes at 1.86C. Assuming molality equal to molarity, pH of CH3COOH of solution is
(A) 2 (B) 3
(C) 3.2 (D) 4.2
12. pH of a 0.1M monobasic acid is found to be 2. Hence its osmotic pressure at a given temperature. TK is
(A) 0.1 RT (B) 0.11 RT
(C) 1.1 RT (D) 0.01 RT
13. Lowering of vapour pressure due to a solute in 1 molal aqueous solution at 100C is
(A) 13.44 torr (B) 14.12 torr
(C) 312 torr (D) 352 torr
14. If relative decrease in V.P. is 0.4 for a solution containing 1 mol NaCl in 3 mol of H2O, NaCl is………….% ionized
(A) 60% (B) 50%
(C) 100% (D) 40%
15. Which has maximum osmotic pressure at temperature T?
(A) 100 mL of 1 M urea solution
(B) 300 mL of 1 M glucose solution
(C) mixture of 100 mL of 1 M urea solution and 300 mL of 1 M glucose solution
(D) all are isotonic
16. V.P of pure A =100 mm Hg
V.P. of pure B = 150 mm Hg
Distillate of vapours of a solution containing 2 mol of A and 3 mol of B will have total vapour pressure, approximately, on condensation
(A) 135 mm (B) 130 mm
(C) 140 mm (D) 145 mm
17. The degree of dissociation ‘’, of a weak electrolyte is
(A) (B)
(C) (D)
18. Which of the following azeotropic solutions has the B.P less than B.P of the constituent A and B?
(A) CHCl3 and CH3COCH3 (B) CS2 and CH3COCH3
(C) CH3CH2OH and CHCl3 (D) CH3CHO and CS2
19. A solution contains 0.1 mol of acetamide in 1 L of glacial acetic acid. When the solution is cooled, the first crystal that appeared at the freezing point contains the molecules of
(A) acetamide only
(B) acetic acid only
(C) both acetamide and acetic acid
(D) either acetamide and acetic acid depending upon the conditions of the experiment
20. As2S3 sol is
(A) positive colloid (B) negative colloid
(C) neutral colloid (D) none of the above
21. Which one of the following is a lyophilic colloid?
(A) Milk (B) Gum
(C) Fog (D) Blood
22. Cellulose dispersed in ethanol is called
(A) emulsion (B) micelle
(C) collodion (D) hydrophilic sol
23. Which of the following can act as a protective colloid?
(A) Gelatin (B) Silica gel
(C) Oil-in-water emulsion (D) All of the above
24. Which of the following will have the highest coagulation power for As2S3 colloid?
(A) (B)
(C) (D)
25. Absorption is accompanied by
(A) decrease in entropy of system (B) decrease in enthalpy
(C) the value TDS is negative (D) all of the above
26. Which acts as poison for Pd charcoal in Lindlar catalyst?
(A) BaSO4 (B) Quinoline
(C) Both (A) and (B) (D) None of the above
27. Which is an example of auto catalysis?
(A) Hydrolysis of methyl acetate (B) Decomposition of T.N.G
(C) Oxidation of oxalic acid by KMnO4 (D) All of the above
28. Smoke has generally blue tings. It is due to
(A) scattering (B) coagulation
(C) Brownian motion (D) electro-osmosis
29. Collodial system is a two phase system. Point out which of the following combination cannot be considered as colloidal system?
(A) Solid – solid (B) Liquid – liquid
(C) Gas – gas (D) Liquid – gas
30. Which plot is the adsorption isobar for chemisorption?
(A)
(B)
(C)
(D)
31. Zeolites are used as catalyst is
(A) petrochemical industries during cracking
(B) in the preparation of H2SO4
(C) in the hydrolysis of ester
(D) all of the above
32. Ferric chloride is applied to stop bleeding cut because
(A) Fe3+ ion coagulates blood, which is a negatively charged sol
(B) Fe3+ ion coagulates blood, which is a positively charged sol
(C) Cl- coagulates blood, which is a positively charged sol
(D) Cl- ion coagulates blood, which is a negatively charged sol
33. The protective action of different colloids is expressed in terms of
(A) oxidation number (B) atomic number
(C) gold number (D) Avogadro’s number
34. Tyndall effect depends upon the
(A) charge on the colloidal particles
(B) osmotic pressure of colloidal solution
(C) difference between the refractive indices of dispersed phase and dispersion medium
(D) size of colloidal particles
35. Colloidal sulphur is obtained when
(A) sulphur is heated gradually to a high temperature
(B) sulphur is heated with dilute sulphuric acid
(C) hydrogen sulphide is passed through an aqueous solution of nitric acid
(D) sulphur is warmed with carbon disulphide
36. When a colloidal solution is observed under an ultramicroscope, we can see
(A) light scattered by colloidal particles
(B) size of colloidal particles
(C) shape of the colloidal particles
(D) relative size of colloidal particles
37. What is the correct sequence of the increasing effectiveness of the following electrolyte for the coagulation of ferric hydroxide sol?
1. AlPO4 2. CuSO4 3. SnCl4
Select the correct answer using the codes given below:
Codes:
(A) 3, 2, 1 (B) 1, 2, 3
(C) 1, 3, 2, (D) 2, 3, 1
38. On addition of 1 ml of 10% aq. NaCl solution to 10 ml red gold sol in presence of 0.250 g of starch, the colour changes from red to blue (or coagulation). Starch has the gold number
(A) 0.025 (B) 0.25
(C) 250 (D) 2.5
39. Which of the following electrolyte is least effective in causing flocculation of Fe(OH)3 sol?
(A) K3[Fe(CN)6] (B) K2CrO4
(C) KBr (D) K2SO4
40. On breaking a cubic solid (edge = 1 m) into fine cubic particles of edge 1 mm, surface becomes
(A) 100 times (B) 1,000,000 times
(C) 100 times (D) remains unchanged
41. In the process of extraction of gold
Roasted ore + CN-1 + H2O
Identify the complexes [X] and [Y]
(A)
(B)
(C)
(D)
42. In alumino thermite process, aluminimum acts as
(A) oxidizing agent (B) flux
(C) reducing agent (D) a solder
43. In which of the following minerals Al is not present
(A) cryolite (B) mica
(C) feldspar (D) fluorspar
44. An important ore of magnesium is
(A) malachite (B) cassiterite
(C) carnalite (D) galena
45. Pyrolusite is a/an
(A) oxide ore (B) sulphide ore
(C) carbide ore (D) none
46. Malachite is an ore of
(A) iron (B) zinc
(C) copper (D) mercury
47. Which of the following metals is most abundant in earth’s crust is?
(A) Mg (B) Na
(C) Al (D) Fe
48. In the metallurgy of which of the following cupellation process is used
(A) Cu (B) Ag
(C) Fe (D) Al
49. Smelting involves reduction of metal oxide with
(A) C (B) CO
(C) Mg (D) Al
50. Zone refining has been employed for preparing ultra pure samples
(A) Cu (B) Zn
(C) Ge (D) Al
51. The process of concentrating Au and Ag ores is based on their solubility in
(A) NH3 (B) HNO3
(C) HCl (D) KCN
52. Galena is an ore of
(A) Pb (B) Hg
(C) Cu (D) Na
53. The extraction of which of the following metals involves bessemerisation
(A) Fe (B) Ag
(C) Al (D) Na
54. The metal always found in the free state is
(A) Au (B) Ag
(C) Cu (D) Na
55. Thermal decomposition method is used to purify
(A) Ni (B) Cr
(C) Sn (D) Pb
56. In the extraction of iron, slag produced is
(A) CO (B) FeSiO3
(C) MgSiO3 (D) CaSiO3
57. Which of the following metals is extracted has the electrometallurgical method?
(A) Cu (B) Fe
(C) Na (D) Ag
Multiple choice questions with more than one option correct
58. 1 mol benzene ( and 2 mol toluene will have
(A) total vapour pressure 38 mm
(B) mol fraction of vapours of benzene above liquid mixture is 7/19
(C) positive deviation from Raoult’s law
(C) negative deviation from Raoult’s law
59. Consider following solutions:
I : 1 M aq. Glucose
II : 1M aq. Sodium chloride
III : 1M benzoic acid in benzene
IV : 1 M ammonium phosphate
Select correct statement (s)
(A) all are isotonic solutions (B) III is hypotonic of I, II, IV
(C) I, II, IV are hypertonic of III (D) IV is hypertonic of I, II, III
60. Which is / are correct statement(s)?
(A) when mixture is less volatile, there is positive deviation from Raoult’s law
(B) when mixture is more volatile, there is negative deviation from Raoult’s law
(C) when mixture is less volatile, there is negative deviation from Raoult’s law
(D) when mixture is more volatile, there is positive deviation from Raoult’s law
61. At 35C, the vapour pressure of CS2 is 512 mm Hg and of acetone is 344 mm Hg. A solution of CS2 and acetone in which the mol fraction of CS¬2 is 0.25, has a total vapour pressure of 600mm Hg. Which of the following statement is/are correct?
(A) a mixture of 100 mL of acetone and 100 mL of CS2 has a volume of 200 mL
(B) when acetone and CS2 are mixed at 35C, heat must be absorbed in order to produce a solution at 35C.
(C) when acetone and CS2 are mixed at 35C, heat is released
(D) there is negative deviation from Raoult’s law
62. Which of the following statements are correct for the rock-salt structure?
(A) The tetrahedral sites are smaller than octahedral sites
(B) The octahedral sites are occupied by cations and the tetrahedral sites are empty
(C) The radius ratio is 0.732 (maximum value)
(D) The radius ratio is 0.999 (maximum value)
63. Aluminium is purified by
(A) Baeyer’s process (B) Ostwald’s process
(C) Hoope’s process (D) Serpeck’s process
64. If P° and Ps are the vapour pressures of the solvent and its solution respectively and N1 and N2 are the mole fractions of the solvent and solute respectively, then
(A) Ps = P° N2 (B) P° - Ps = P° N2
(C) Ps = P° N1 (D) (P° - Ps) / Ps = N1 / (N1 + N2).
65. Ideal solution is formed when its components
(A) have zero heat of mixing (B) have zero volume change
(C) obey Raoult’s law (D) can be converted into gas
66. Metallic gold crystallizes in FCC lattice. The length of its unit cell is 5.656 Å. The closest distance between gold atoms is
(A) 4 Å (B) 2.878 Å
(C) 3.56 Å (D) 2 Å
67. A substance AxByCzDa crystallizes in close packed structure (CCP). A atoms are present at the corners, B at the centre of cube, C at all face & D at all the edges what is the formula of compound
(A) A2BC3D3 (B) ABC3D2
(C) ABC3D3 (D) none of the above in correct
68. A mineral having the formula AB2 crystallizes in the c.c.p lattice with A atom occupying the lattice points. The CN of A is 8 and that of B is 4. What % of the tetrahedral site is occupied by B atom?
(A) 25% (B) 50%
(C) 75% (D) 100%
69. Which is/are correct statements?
(A) 1 L of 1N H3PO4 solution contains one – third of molecular weights when it is completely neutralized by NaOH
(B) 1 L of 1N H3PO4 solution contains 1 mole of H3PO4 when it is reduced to
(C) 1 L of 1N H3PO4 solution contains 0.5 mole of H3PO4 when it is reduced to
(D) H3PO4 is a monobasic acid
70. The capacity of an ion to coagulate a colloidal solution depends on
(A) Its shape (B) Amount of its charge
(C) The sign of the charge (D) None
71. The migration of colloidal particles under the influence of an electric field is known as
(A) electro-osmosis (B) cataphoresis
(C) electrodialysis (D) electropheresis
72. In the depression of freezing point experiment, it is found that
(A) the vapour pressure of the solution is less than that of pure solvent
(B) the vapour pressure of the solution is more than that of pure solvent
(C) only solute molecules solidify at the freezing point
(D) only solvent molecules solidify at the freezing point
73. Which statement/s is/are correct?
(A) Physical adsorption is multilayer non-directional & non specific
(B) chemical adsorption takes more time to attain equilibrium
(C) physical adsorption is due to free valence of atoms
(D) chemical adsorption is stronger than physical adsorption
74. 1 mol of [AgI]Ag+ sol is coagulated by
(A) 1 mol of KI (B) 500 mL of 1M K2SO4
(C) 300 mL of 1 M Na3PO4 solution (D) 1 mol of AgI
75. On adding AgNO3 solution into KI solution, a negatively charged colloidal sol is obtained when they are in
(A) 100 mL of 0.1 M AgNO3 + 100 mL of 0.1 M KI
(B) 100 mL of 0.1 M AgNO3 + 100 mL of 0.2 M KI
(C) 100 mL of 0.2 M AgNO3 + 100 mL of 0.1 M KI
(D) 100 mL of 0.1 M AgNO3 + 100 mL of 0.15 M KI
76. Which is/are true statements?
(A) water vapour is absorbed by anhydrous calcium chloride but adsorbed by silica gel
(B) NH3 is absorbed by water but adsorbed by charcoal
(C) sugar is decolorized by animal charcoal based on adsorption
(D) water is absorbed by conc. H2SO4
77. Anionic surfactants are
(A) C15H31COONa (B)
(C) C18H37NH3Cl (D) All
78. Cationic surfactants are
(A) C17H35COONa (B)
(C)
(D) C16H33N(CH3)3Cl
79. Catalyst increases the rate
(A) by decreasing Ea (B) by increasing Ea
(C) by decreasing entropy (D) by increasing entropy
80. Which is/are correct statements about the role of a catalyst in a reaction?
(A) It is a reactant in a rate-determining step and then a product of some subsequent step
(B) It provides an alternate mechanism with a lower energy of activation
(C) It increases the rate of chemical reaction but does not itself undergo a permanent change during the course of the reaction
(D) Enzyme catalysts are protein molecules
81. Which of the following forms/s ideal solution?
(A) C6H5Cl C6H5Br (B) C6H5 C6H5CH3
(C) Hexane – Heptane (D) None
82. The colligative properties of a solution are
(A) molality (B)
(C) proportional to each other (D) none
Comprehension-I
Read the paragraph carefully and answer the following questions:
In HCP or CCP, constituent particles occupy 74% of the available space. The remaining space (26%) in between the spheres, remains unoccupied and is called interstitial voids or holes.
Considering the close packing arrangement, each sphere in the second layer rests on the hollow space of the first layer, touching each other. The void created is called tetrahedral void.
If R is the radius of the spheres in the close packed arrangement then,
R (radius of tetrahedral void) = 0.225 R
In a close packing arrangement, the interstitial void formed by the combination of two triangular voids of the first and second layer is called octahedral void. Thus, double triangular void is surrounded by six spheres. The centre of these spheres on joining, forms octahedron. If R is the radius of the sphere in a close packed arrangement then,
R (radius of octahedral void = 0.414 R).
83. In the figure given below, the site marked as S is a
(A) tetrahedral void (B) cubic void
(C) octahedral void (D) None of the above
84. If the anions (A) form hexagonal close packing and cations (C) occupy only 2/3rd octahedral voids in it, then the general formula of the compound is
(A) AB (B) A3B2
(C) A2B (D) AB3
85. In the spinel structure, oxide ions are cubic close packed whereas 1/8th of tetrahedral voids are occupied by A2+ cations and 1/2 of octahedral voids are occupied by B3+ cations. The general formula of the compound having spinel structure is
(A) A2B2O4 (B) AB2O4
(C) A2B4O2 (D) A4B2O2
86. Mark the false statement:
(A) CsCl crystal shows Schottky defect.
(B) Crystals having F–centres are coloured and paramagnetic.
(C) Photosensitivity of AgBr is due to the presence of Frenkel defect in this crystal.
(D) None of the above
87. In Schottky defect
(A) cations are missing from the lattice sites and occupy the interstitial sites
(B) equal number of cations and anions are missing
(C) anions are missing and electrons are present in their place
(D) equal number of extra cations and electrons are present in the interstitial sites
Comprehension-II
By X – rays studies, the packing of atoms in a crystal of gold is found to be layers such that starting from only layer, every fourth layer is found to be exactly identical. The density of gold is found to be 19.4 g cm3 and its atomic mass is 197 amu.
88. The coordination number of gold atom in the crystal is
(A) 4 (B) 6
(C) 8 (D) 12
89. The fraction occupies by gold atoms in the crystal is
(A) 0.52 (B) 0.68
(C) 0.74 (D) 1.0
90. The approximate number of unit cells present in 1 g of gold is
(A) 3.06 1021 (B) 1.53 1021
(C) 3.82 1020 (D) 7.64 1020
91. The length of edge of unit cell will be
(A) 407 pm (B) 189 pm
(C) 814 pm (D) 204 pm
92. Assuming gold atom to be spherical, its radius will be
(A) 203.5 pm2 (B) 143.9 pm
(C) 176.2 pm (D) 287.8 pm
Comprehension - III
Read the paragraph carefully and answer the following questions:
The vapour pressure of a solvent in a solution is lower than that of pure solvent, at the same temperature. A higher temperature is needed to raise the vapour pressure up to the atmospheric pressure, when boiling begins. However, increase is small, like 0.1 molkg–1 aqueous sucrose solution boils at 100.05oC. Sea water, an aqueous solution, which is rich in Na+ and Cl– ions, freezes about 1oC lower than frozen water. At the freezing point of a pure solvent, the rates at which two molecules stick together to form the solid and leave it to return to liquid state are equal when solute is present. Fewer solvent molecules are in contact with surface of solid. However, the rate at which the solvent molecules leave the surface of solid remains unchanged. That is why temperature is lowered to restore the equilibrium. The freezing point depression in an ideal solution is proportional to molality of the solute.
93. An aqueous solution of 0.1 molkg–1 concentration of sucrose should have freezing point of (Kf = 1.86)
(A) –0.2oC (B) 0.2oC
(C) 2oC (D) –2oC
94. When 250 mg of eugenol is added to 100 gm of camphor (Kf = 39.7), it lowered the freezing point by 0.62oC. The molar mass of eugenol is
(A) 1.6 × 102 gm/mole (B) 1.6 × 104 gm/mole
(C) 1.6 × 103 gm/mole (D) 200 gm/mole
95. 20 gm of binary electrolytic (M.W. = 100) are dissolved in 500 gm of water. The freezing point of solution is -0.74oC. Kf = 1.86 K molality-1. The degree of ionization of electrolyte is
(A) 50% (B) 75%
(C) 100% (D) zero
Comprehension - IV
The process of cast iron extraction can be briefed as follows:
Read the above process for cast iron extraction carefully and give the answers to the question thereafter.
96. The reasons for using hydraulic and magnetic separation processes are mainly due to
(A) Ores are mainly carbonates and oxides or hydrated oxides & magnetic ore, magnetite (Fe3O4) is there
(B) Oil floatation process is expensive
(C) Oil floatation process is applicable only on sulphide ores
(D) Oxides and carbonates have silica as impurity
97. Roasting is done in the 2nd step instead of calcinations alone, because
(A) In roasting process, all FeO will be converted to Fe2O3 which can’t react with silica to form slag.
(B) Maximum impurities will be gone off as gaseous oxides
(C) Due to escape of various gases, entire mass become porous which facilitates the subsequent reduction of iron oxide
(D) All the above
98. In the reduction process hot air (O2) blast is introduced into the furnace as
(A) Coke forms CO which is better reducing agent, with air
(B) With the increase in temperature reducing property of coke decreases
(C) When coke gets converted into CO, huge amount heat generates which keeps the mass in the furnace molten.
(D) All of the above
99. The function of lime stone in the blast furnace is
(A) To remove SiO2 & S (if any) (B) Forms CO with coke
(C) Lowers the m.pt. of the iron oxides (D) (A) & (B)
100. Match List - I with List - II
List - I List - II
(A) Zinc blende structure 1. oxide ions in hcp and 2/3rd of octahedral voids occtupied by trivalent cation.
(B) Anti-fluorite structure 2. anion in FCC arrangement and alternate tetrahedral voids occupied by bivalent cation.
(C) Corundum structure 3. Oxide ions in CCP, bivalent cations in corners and one tetravalent cation in the octahedral void created by oxide ions.
(D) Pervoskite structure 4. Anions in FCC and cations in all tetrahedral voids
101. Match the items in List - I with items in List – II.
List – I (Method) List – II (Reaction)
(A) Mond’s process 1.
(B) van Arkel de Boer Process 2.
(C) Thermite Process 3.
(D) Kroll process 4.
5.
102. Match the solutions in Column-I with their nature in Column-II
List – I List – II
(A) Benzene + toluene 1. Non-ideal solution
(B) Ethanol + water 2. Ideal solution
(C) Benzene + chloroform 3. Hmix > 0
(D) Carbon tetrachloride
+ chloroform 4. Hmixing = 0
103. Match the terms of List-I with those of List-II
List – I List – II
(A) Coagulation 1. Scattering of light
(B) Peptization 2. Purification of colloidal solution
(C) Tyndall effect 3. Addition of electrolyte
(D) Dialysis 4. precipitation of colloidal solution
ANSWERS TO WORK BOOK
Subjective:
Board Type Questions
1. For 0.01 M solution
p1 = C1RT
= 0.01 ´ 0.0821 ´ 300 = 0.2463 atm
for 0.001 M solution
p2 = C2RT
= 0.001 ´ 0.0821 ´ 300 = 0.02463 atm
2. Let the molecular weight of substance = m
From Raoult’s Law
=
on solving, we get
m = 65.25
3. 38% by weight means 38 gm H2SO4 in 100 – 38 = 62 gm water
So molality of H2SO4 solution =
=
DTf = i Kf Cm
= 2.5 ´ 1.86 ´ = 29.08K
Tb = 273 – 29.08 = 243.92 K
4. Normal molecular weight of Hg(CN)2 = 200.6 + 2 (12 + 14) = 252.6
Observed molecular weight we can calculate from the data given according to the equation
= 234.37
Mercuric cyanide dissociates as follows
Hg(CN)2 Hg+2 + 2CN–
1 0 0 (before dissociation)
(1 - a) a 2a (after dissociation)
Þ a = 0.0389
Observed molecular weight = 234.37
Degree of dissociation = 3.89%
5. 0.5% (wt. / vol) solution means 0.5 gm of cellulose acetate is dissolved in 100 ml solution.
Osmotic pressure = 23 mm of pure acetone
p = 2.3 Cm of pure acetone.
= cm of Hg = 0.1522 cm of Hg
p = atm = 0.002 atms
Let the molecular weight of the cellulose acetate be m
Here, number of mole of cellulose acetate (n) =
Volume = v = 100 ml = 0.1 lit
R = 0.082 Lit atm mol–1 K–1, T = ( 27 + 273) = 300 K
Osmotic pressure (p) = ´RT
Þ 0.002 = ´ 0.0821 ´ 300
\ m = 61575
6. (a) The cubic unit cell has 8 atoms at eight corners. Each atom is shared by 8 unit cells.
\
(b) The body centred cubic cell consist of 8 atoms at the corners and one atom at centre.
\
(c) The face centred cubic unit cell consist of 8 atoms at the eight corners and one atom at each of the six faces. The atom at the face is shared by two unit cells.
\
7. A atoms are at eight corners of the cube.
Therefore, the number of A atoms in the unit cell = 8/8 = 1
B atoms are at the face centre of six faces.
Therefore, its share in the unit cell = 6/2 = 3
The formula is AB3.
8. (a)
(b)
(c)
9. A body – centred cubic unit cell contains 8 atoms at the 8 corners and one in the centre.
= 1.002 g cm-3
10. The distance between Li+ and Cl- ion can be derived as half of the edge length of cube.
\
\
The radius of Cl- =
11. The number of units of AB in a unit cell (f.c.c) = 4
Radius of cation A+ = 100 pm = 100 ´ 10-10 cm
Radius of r+/r- for octahedral co-ordination = 0.414
Hence, Radius of the anion (B-) =
12. Radius ratio =
The radius ratio lying in between 0.414 and 0.732 and thus represents for octahedral voids. Also B- is larger than A+ and thus B- forms closed packed structure and A+ occupies the void space. Thus, co-ordination number of cation A+ in AB is six.
13. 3
14. 2.907 A°
15. Carbon play two roles in the metallurgy of zinc.
(a) It reduces zinc oxide to zinc.
ZnO + C ¾¾® Zn + CO
ZnO + CO ¾¾® Zn + CO2
(b) It reduces CO2 into CO which is used as fuel.
CO2 + C ¾¾® 2CO
16. MgO is basic is nature, i.e. removes acidic impurities present in cast iron used for making steel.
MgO + SiO2 ¾¾® MgSiO3
3MgO + P2O5 ¾¾® Mg3(PO4)2
MgO is also refracting material as it can tolerate very high temperature of the furnace.
17. Air is necessary to convert impurities such as sulphur, arsenic and antimony into volatile oxides and for partial oxidation of pyrite ore. Calcination does not use oxygen while roasting is done in presence of air. Thus roasting and calcinations is done in the metallurgy of copper.
18. The concentrated ore is roasted in the reverbatory furnace in a current of air. The volatile impurities such as free sulphur, arsenic and antimony are removed as volatile oxides and the ore is partially oxidised.
4As + 3O2 ¾¾® 2As2O3, 4Sb + 3O2 ¾¾® 2Sb2O3, S + O2 ¾¾® SO2
2CuFeS2 + O2 ¾¾® Cu2S + 2FeS + SO2
2CuFeS2 + 4O2 ¾¾® Cu2S + 2SO¬2¬
2Cu2S + 3O2 ¾¾® 2Cu2O + 2SO2
A mixture of sulphides and oxides is formed. The Cu2O so formed reacts with unreacted Cu2S to form copper.
Cu2S + 2Cu2O ¾¾® 6Cu + SO2
19. Zinc is cheaper as well as stronger redcuing agent in comparison to copper.
Zn + 2[Ag(CN)2]- ¾¾® 2Ag + [Zn(CN)4]-2
20. Lime stone is added as a flux, it is decomposed in the furnace into CaO & CO2, CaO reacts with gangue silica and forms impossible slag
CaCO3 ¾¾® CaO + CO2
CaO + SiO2 ¾¾® CaSiO3
Slag
21. ‘A’ is sodium carbonate
Ca2B6O11 + 2Na2CO3 ¾¾® Na2B4O7 + 2NaBO2 + 2CaCO3
‘B’ is either con. H2SO4 or HCl.
Na2B4O7 + H2SO4 + 5H2O ¾¾® Na2SO4 + 4H¬3BO3
Na2B4O7 + 2HCl + 5H2O ¾¾® 2NaCl + 4H¬3BO3
23. Argentite ore is Ag2¬S.
Ag2S + 4NaCN
2Na[Ag(CN)2] + Zn ¾¾® Na2[Zn(CN)4] + 2Ag
22. Haematite Fe2O3 on burning with coke and lime at 2000°C results in the following.
C + O2 ¾¾® CO2, CO2 + C ¾¾® 2CO
3CO + FeO3 ¾¾® 2Fe + 3CO2 (Reducing of Fe2O3 to form steel)
SiO2 + CaO ¾¾® CaSiO3 (Slag, CaSiO3) is used as building materials.
SiO2 + CaO ¾¾® CaSiO3 [slag] is used as building material.
24. (i) The path of light becomes visible because colloidal particles scatter light (Tyndall effect).
(ii) Fe(OH)3 gets coagulated.
25. This is because dialysis helps in removing undesirable ions from a colloidal preparation in order to stabilize the colloid.
26. The extent of adsorption of a gas on a solid is affected by (i) nature of the gas (ii) nature of the solid (iii) specific area of the solid (iv) pressure of the gas (v) temperature (vi) activation of adsorbent.
27.
Where m is the mass of adsorption and x that of adsorbate, p is the pressure of the gas and n is an integer.
30. Fe(OH)3 is positively charged sol whereas As2S3 in a negatively charged sol. On mixing, charges are neutralized and so coagulation occurs.
31. Colloidal particles move towards the appositively charged electrode, we get neutralized and coagulated (electrophoresis).
IIT Level Questions
42. f.c.c unit cell length = 3.5A°
b.c.c unit cell length = 3.0 A°
Now n1 for f.c.c = 4; Also V1 = a3 = (3.5 ´ 10-8)3
n2 for b.c.c = 2; Also V2 = a3 = (3.0 ´ 10-8)3
43. Doping of SrCl2 to NaCl brings in replacement of two Na+ ion by each Sr2+ ion, but each Sr2+ occupies only one lattice point. This produces one cation vacancy.
Thus, doping of 10-3 mole of SrCl2 in 100 mole
NaCl will produce cation vacancies = 10-3
\ 100 mole NaCl will have cation vacancies after doping = 10-3
\ 1 mole NaCl will have cation vacancies =
\ Total cationic vacancies = 10-5 ´ Av. No
= 6.02 ´1018
44. 290 pm
45. 1.37 A°
47. Due to ionization of KCl
KCl ¾¾® K+ + Cl–
Initial moles 1 0 0
Moles after dissociation 1–a a a
\ i = = 1+ a
From question, degree of ionization = a = 0.86
\ i = 1+ 0.86 = 1.86
For Osmotic pressure of glucose,
For 4% glucose solution,
Weight of glucose = 4 gm, volume of solution = V = 1L = 1dm3
Molecular weight of glucose C6H12O6= m = 180
\ pglucose = n ´ ´ RT, where pglucose = osmotic pressure of glucose
= ´ ´ R ´ T = ´ ´ RT
Similarly, pKCl = = 1.86 ´ n ´ ´RT= 1.86 ´ ´ ´ RT
= 1.86 ´ ´ ´RT
As both solutions are isotonic
\pKCl = pglucose
1.86 ´ ´ RT = ´ RT
\ W1 = ´ = 8.9 gm
48. From question, molality of solution = Cm = 0.1
Depression in freezing point = DTf = 0.558°C
Kf (H2O) = 1.86 kg mol–1 K–1
As we know that
DTf = Kf ´ i ´ Cm , Where i = Vant Hoff’s factor
0.558 = 1.86 ´ 0.1 ´ i
\ i = = 3
or, i » 3 indicates that complex ionize to form three ions since co ordination number is 6 hence x = 5
i.e., CoCl3.5NH3 ¾® [Co(NH3)5Cl]++ + 2Cl–
¯ ¯
1 Cation 2 anions
So, the complex is [Co(NH3)5Cl]Cl2
49. The data on osmotic pressure are:
w2 = 6g
V = 250 cm3 = 0.25 litre
P = 4.5 atm
T = 27 + 273 = 300K
R = 0.0821 litre atm/degree/mole
Van’t Hoff equation for osmotic pressure is
PV = nRT
\ 4.5 ´ 0.25 = n ´ 0.0821 ´ 300
i.e. 0.0457 mole of the solute are present in 250 ml of water (or 250 g of water)
\ Molality of the solution
i.e. m = 0.1828
Kb = 0.52°C/1000 g (given)
\ DTb = Kb ´ m
= 0.52 ´ 0.1828 = 0.095°C
\ Boiling point of solution
= 100.95°C
51. Step I: to calculate molality of the solution from boiling point data: We are given that
Kb = 0.512°C
Using the formula
where m is the molality
Step II: To calculate the depression in freezing point: We are given that Kf = 1.86°C
M = 0.25 (calculated above)
\ DTf = Kf ´ m = 1.86 ´ 0.25 = 0.465°C
\ Freezing point of the solution
= - 0.465°C
Objective:
Single Correct Questions
1. B 2. D 3. A 4. B 5. B 6. A 7. C 8. A 9. B 10. B 11. B 12. A 13. A 14. C 15. D 16. A
17. B 18. C 19. B 20. B
21. B 22. C 23. A 24. C
25. D 26. C 27. D 28. A 29. C 30. C 31. A 32. A
33. C 34. C 35. C 36. A
37. B 38. C 39. C 40. B
41. A 42. C 43. D 44. C
45. A 46. C 47. C 48. B
49. A 50. C 51. D 52. A
53. A 54. A 55. A 56. D
57. C
Multiple Correct Questions
58. A, B 59. B, C, D 60. C, D 61. B, D
62. A,B,C 63. A, C, D 64. B, C 65. A, B, C
66. A 67. C 68. D 69. A, C
70. A, B 71. B, C, D 72. C, D 73. B, D
74. A, B 75. B,D 76. A,B,C,D 77. A,B
78. C,D 79. A,C 80. A,B,C, D 81. A, B, C
82. A, B, C
Comprehension
83. C 84. B 85. B 86. D 87. B 88. D 89. C 90. D
91. A 92. B 93. A 94. A 95. D 96. A 97. D 98. C 99. D
100. A – 2; B – 4; C – 1; D – 3
101. A – 3; B – 5; C – 1; D - 2
102. A - 2, 4; B - 1, 3; C – 1; D - 4
103. A – 3, 4; B – 3; C – 1; D – 2
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