DPP-51 to 52-(Physical)-Physical Chemistry

DAILY PRACTICE PROBLEMS (DPP) Subject : Physical/Inorg.Chemistry Date : DPP No. 51 to 52 Class : XIII Course : DPP No.51 DPP No.1 Total Marks : 38 Max. Time : 38 min. Single choice Objective ('–1' negative marking) Q.1 to Q.10 (3 marks 3 min.) [30, 30] Subjective Questions ('–1' negative marking) Q.11 to Q.12 (4 marks 4 min.) [8, 8] 1. The solubility of A X is y mol dm 3 . Its solubility product is : (1) 6 y4 (2) 64 y4 (3) 36 y5 (4) 4 y3 2. The solubility of sparingly soluble electrolyte MmAa in water is given by the expression :  (1) s =  Ksp m  a   (2) s =  Ksp 1/ m  a   (3) s =  Ksp m  a   (4) s =  Ksp 1/ m  a   mm aa   mm aa   ma am   ma am          3. Three sparingly soluble salts M2X, MX and MX3 have the solubility product are in the ratio of 4: 1 : 27. Their solubilities will be in the order (1) MX3 > MX > M2 X (2) MX3 > M2X > MX (3) MX > MX3 > M2X (4) MX > M2X > MX3 4. A particular saturated solution of silver chromate, Ag CrO , has [Ag+]= 5×10–5 and [CrO 2–] = 4.4×10–4 M. What is value of Ksp for Ag2CrO4 ? (1) 1.1 × 10–12 . (2) 1.5 × 10–12 (3) 2 × 10–6 (4) 1 × 1012. 5. If the solubility product of silver oxalate is 5 × 10–10, what will be the weight of Ag C O in 2.5 litres of a saturated solution ? (Ag = 108, C = 12, O = 16). 2 2 4 (1) 0.50 gm (2) 0.38 gm (3) 0.30 gm (4) 0.45 gm. 6. A student wants to prepare a saturated solution of Ag+ ion . He has got three samples AgCl (K = 10 10) , 13 11 AgBr (Ksp = 1.6 × 10 ) and Ag CrO (Ksp = 3.2 × 10 ) . Which of the above compound will be used by him using minimum weight to prepare 1 lit. of saturated solution. (1) AgCl (2) AgBr (3) Ag2 CrO4 (4) all the above . 7. If the solubility of Ag2SO4 in 10 M Na SO solution be 2 × 10 M then K of Ag SO will be: –2 –8 2 4 (1) 32 × 10–24 (2) 16 × 10–18 (3) 32 × 10–18 (4) 16 × 10–24 8. The solubility of CaF2 NaF solution. in water at 1518ºC is 2 × 10–4 mole/litre. Calculate K of CaF2 and its solubility in 0.1M (1) 3.5 × 108 mole/litre (2) 3.0 × 109 mole/litre. (3) 3.3 × 10–9 mole/litre (4) 4.0 × 107 mole/litre 9. Calculate F— in a solution saturated with respect of both MgF and SrF2. Ksp (MgF ) = 9.5 x 10-9, K (SrF ) = 4 x 10-9. (1) 3 × 10–3 M. (2) 4 × 10–2 M. (3) 3.5 × 10–3 M (4) 1 × 10–3 M. 10. A solution is saturated with respect to SrCO & SrF . The [CO 2] was found to be 1.2 x 103 M. The 3 2 3 concentration of F in the solution would be : K (SrCO ) = 10–9, K (SrF ) = 3 × 10–11. (1) 3 x 103 M (2) 2 x 102 M (3) 6 x 102 M (4) 6 x 107 M 11. Calculate the solubility of AgCl (s) in (a) pure water (b) 0.1 M NaCl (c) 0.01 M CaCl2 at 25º C . Ksp (AgCl) = 2.56  10 10. Comment on the influence of [ Cl ] on the solubility of AgCl. 12. Find the solubility of CaF2 in 0.5 M solution of CaCl2 and water. How many times in solubility in the second case greater than in the first ? Ksp (CaF ) = 3.2 × 10–11. DPP No.52 DPP No.2 Total Marks : 38 Max. Time : 38 min. Single choice Objective ('–1' negative marking) Q.1 to Q.11 (3 marks 3 min.) [33, 33] Subjective Questions ('–1' negative marking) Q.12 (4 marks 5 min.) [4, 5] 1. The standard oxidation potentials, E°, for the half-reaction are as Zn = Zn2+ + 2e– ; E° = + 0.76 V Fe = Fe2+ + 2e– ; E° = + 0.41 V the E°cell is - Fe+2 + Zn Zn2+ + Fe gSaA (1) –0.35 V (2) + 0.35 V (3) +1.17 V (4) – 1.17 V 2. From the following E° values of half cells - (i) A + e–  A¯ ; (iii) C¯ + 2e–  C3– ; E° = – 0.24 V E° = –1.25 V (ii) B¯ + e–  B2– ; (iv) D + 2e–  D2– ; E° = + 1.25 V E° = + 0.68 V What combination of two half cells would result in a cell with the largest potential (1) (ii) and (iii) (2) (ii) and (iv) (3) (i) and (iii) (4) (i) and (iv) 3. The Ni/Ni2+ and F–/F electrode potentials are listed as +0.25 V and –2.87 V respectively (with respect to the standard hydrogen electrode). The cell potential when these are coupled under standard conditions is (1) 2.62 V and dependent on the reference electrode chosen. (2) 3.12 V and independent of the reference electrode chosen. (3) 3.12 V and dependent on the reference electrode chosen. (4) 2.62 V and independent of the reference electrode chosen. 4. For the cell prepared from electrode A and B, electrode A : Fe3 Cr2O2 Cr3 , 0 red = + 1.33 V and electrode B : , E0 Fe = 0.77 V, which of the following statement is not correct ? (1) The electrons will flow from B to A (in the outer circuit) when connections are made. (2) The standard emf of the cell will be 0.56 V. (3) A will be positive electrode. (4) None of the above. 5. The standard reduction potentials at 25°C for the following half reactions are given against each - Zn2+(aq) + 2e¯ Zn(s), –0.762 V ; Cr3+(aq) + 3e¯ Cr(s), –0.740 V 2H+ + 2e¯ H (g), 0.00 V ; Fe3+ + e¯ Fe2+, 0.77 V Which is the strongest reducing agent - (1) Zn (2) Cr (3) H (g) (4) Fe3+(aq) 6. Hydrogen gas will not reduce - (1) heated cupric oxide (2) heated feric oxide (3) heated stannic oxide (4) heated aluminium oxide 7. Four colourless salt solutions are placed in separate test tubes and a strip of copper is dipped in each. Which solution finally turns blue ? (use data from electrochemical series) (1) Pb(NO3)2 (2) AgNO3 (3) Zn(NO3)2 (4) Cd(NO3)2 8. Red hot carbon will remove oxygen from the oxide XO and YO but not from ZO. Y will remove oxygen from XO. Use this evidence to deduce the order of activity of the three metals X, Y, and Z putting the most active first - (1) XYZ (2) ZYX (3) YXZ (4) ZXY 9. Two Ist order reactions have half-lives in the ratio 3 : 2. Then the ratio of time intervals t : t , will be? Where 2 t1 is the time period for 25% completion of the first reaction and t2 is time required for 75% completion of the second reaction. [log 2 = 0.3, log 3 = 0.477] (1) 0.199 : 1 (2) 0.420 : 1 (3) 0.273 : 1 (4) 0.311 : 1 10. Identify the correct order of wavelength of light absorbed for the following complex ions. [Co(H O) ]3+ ; Co(CN) ]3– ; [Co(I) ]3– ; [Co(en) ]3+ 2 6 6 6 3 I II III IV (1) III > I > IV > II (2) II > IV > I > III (3) III > I > II > IV (4) I > III > IV > II 11. Which one of the following complexes exhibit chirality ? (1) [Cr(ox) ]3 (2) cis - [PtCl (en)] (3) cis - [RhCl (NH ) ]– (4) mer - [Co(NO ) (NH ) ] 3 2 2 3 2 2 3 3 3 12. If you place the amounts given below in pure water, will all of the salt dissolve before equilibrium can be established, or will some salt remain undissolved ? (a) 4.96 mg of MgF2 in 125 ml of pure water, Ksp = 3.2 x 10-8 (b) 3.9 mg of CaF2 in 100 ml of pure water, Ksp = 4 x 10 -12 Also find the percentage saturation in each case. ANSWER KEY DPP No.-49 1. 1 2. 3 3. 3 4. 3 5. 9.08. 6. 2.76  10 5 mol Lt1. 7. (1) 4.92 (2) 7.56 8. 0.3 mole of C5H5NHCl should be added to 500 ml solution of C5H5N. 9. 4 10. 4 11. 1 ANSWER KEY DPP No.-50 1. 2 2. 3 3. 3 4. 3 5. 1 6. 3 7. 3 8. 3 9. 4 10. 2,3 11. 1,2,4

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