PHYSICAL CHEMISTRY. by: SHAILENDRA KR. Meq. Approach. Classes at: - Topic: Mole Concept

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1 PHYSICAL CHEMISTRY by: SHAILENDRA KR. asses at: - SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna Topic: Mole Concept Meq. Approach 1. The number of milliliter of 1M H 2 solution required to neutralize 10 ml of 1M NaOH (a) 2.5 ml (b) 5.0 ml (c) 10.0 ml (d) 20.0 ml 2. The volume of water which must be added to 40 cc of 0.25 N oxalic acid solution to make its exactly decinormal is (a) 40 cc (b) 30 cc (c) 60 cc (d) 25 cc ml of sodium metal was dissolved in 500 ml of the solution in distilled water. The normality of the solution would be (a) N (b) N (c) N (d) N cc of 0.5 N NaOH added to 10 cc of 3 N H 2 solution and 20 cc of 1N H solution. The solution will be (a) Strongly acidic (b) Alkaline (c) Neutral (d) Fairly acidic 5. The normality of 10 % (wt./vol.) acetic acid is (a) 1 N (b) 10 N (c) 1.7 N (d) 0.83 N 6. H 3 is the tribasic acid and one of its salts is NaH 2. What volume of 1 M NaOH should be added to 12 gm NaH 2 (Mol. wt.=120) to exactly converted it intona 3? (a) 100 cc (b) 300 cc (c) 200 cc (d) 80 cc 7. For preparation of one liter of N/10 H 2 solution we need H 2 equal to (a) 98 cm (b) 4.9 gm (c) 10 gm (d) 2.45 gm 8. The average concentration of Na + in Human blood serum is about 3.4 gm/liter. What is molarity of Na +. (a) 0.15 (b) 2.3 (c) 15.0 (d) H 2 solution used for hair bleaching is sold as a solution of approx 5.0 gm H 2 per 100ml of solution ( Mol-wt of H 2 = 34). The molarity of this hair bleaching solution is approximately (a) 3.0 (b) 1.5 (c) 0.15 (d) The molarity of 98% H 2 by weight (d = 1.8 gm/ml) would be (a) 4 M (b) 18 M (c) 10 M (d) 2 M 11. Kb of CH 3 COO is (If Ka= ) (a) (b) (c) (d) None Page No.: 1

2 12. Which can acts as buffer (a) NH 4 + NH 4 OH (b) CH 3 COOH + CH 3 COONa (c) 40 ml of 0.1 M NaCN+20 ml of 0.1MH (d) All 13. The PH of 10 M H aqueous (a) Less than zero (b) One (c) Two (d) Zero 14. The following equilibrium exist in aqueous solution CH 3 COOH H + + CH 3 COO If dilute H is added to this solution : (a) The equilibrium constant will increase. (b) The equilibrium constant will decrease. (c) Acetate ion concentration will increase. (d) Acetate ion concentration will decrease. 15. In a mixture of CH 3 COOH and CH 3 COONa, the ratio of salt to acid concentration is increased by ten folds. The ph of the solution will increase by (a) Zero (b) 1 (c) 2 (d) The dissociation constant of NH 4 OH is The hydrolysis constant of NH 4 would be (a) (b) (c) (d) For preparing a buffer solution of PH 4 by mixing sodium acetate and acetic acid, the ratio of concentration of salt and acid (Ka=10-5 ) should be (a) 1 : 10 (b) 10 : 1 (c) 100 : 1 (d) 1 : In the hydrolytic equilibrium A - + H 2 O HA + OH - Ka=1.0 x The degree of hydrolysis of M solution of the salt is (a) 10-3 (b) 10-4 (c) 10-5 (d) Which of the following would not change the ph of 10 cm 3 of dil H when added to the acid (a) 5 cm 3 of pure water (b) 20 cm 3 of pure water (c) 10 cm 3 of conc H (d) 20 cm 3 of conc H 20. PH of a soluion of the mixture of 0.1 N H and 0.1 N CH 3 COOH is (Ka of CH 3 COOH is 1.8 x 10-5 ) (a) 1 (b) 2 (c) 1.7 (d) None 21. Equal volumes of 0.1 AgNO 3 and 0.2 M Na are mixed. The concentration of NO 3 ions in the mixture will be (a) 0.1 M (b) 0.05 M (c) 0.2 M (d) 0.15 M liter of a solution of normality N and 2.5 liter of 2 M H are mixed togather. The resultant solution had a normality 5. The value of N is (a) 6 (b) 10 (c) 8 (d) The solution A and B are 0.1 and 0.2 molar of a substance. If 100 ml of A are mixed with 25 ml of B and there is no change in volume, then the final molarity of the (a) 0.15 M (b) 0.18 M (c) 0.12 M (d) 0.30 M 24. If one mol of H 2 reacts with an exess of NaOH, How many mole of water are formed (a) 2 (b) 1 (c) 3 (d) 4 Page No.: 2

3 25. Molecular weight of oxalic acid is 126. The weight of oxalic acid required to neutralise 1000 ml of normal solution of NaOH is (a) 126 gm (b) 63 gm (c) 6.3 gm (d) 12.6 gm 26. How many gm Ag will be formed by adding 1.7 gm of AgNO 3 in exess of H solution. (Mol. wt. of Ag =143.5) (a) gm (b) gm (c) gm (d) Data is insufficient ml of an H solution gave gm of Ag when treated with excess of AgNO 3. The normality of resulting solution is (a) 0.1 (b) 3 (c) 0.3 (d) liter of 18 molar H 2 has been diluted to 100 liter. The normality of the resulting (a) 0.09 (b) 0.18 (c) 1800 N (d) 0.36 N 29. PH of a 10-8 M solution of H in water is (a) 8 (b) -8 (c) Between 7 and 8 (d) Between 6and ml of a solution contains 0.1 M NH M NH 4 OH. Which addition would not change the PH of the solution (a) Adding 1 ml H 2 O (b) Adding 5 ml of 0.1 M NH 4 (c) Adding 5 ml of NH 4 OH (d) Adding 10 ml of 0.1 M NH One liter of water contains 10-7 mol H + ions. Degree of ionisation of water is (a) 1.8 x 10-7 % (b) 1.8 x 10-9 % (c) 3.6 x 10-7 % (d) 3.6 x 10-9 % 32. The PH of water is 7 at 25 o C. If water is (a) 2 log (3/4) heated to 50 o C, which of the following (c) log (1/3) should be true (a) PH will decrease (b) PH will increase (c) PH will remain seven (d) [H + ] will increase but [OH - ] will decrease 33. Decinormal solution of CH 3 COOH ionised to an extent of 1.3 %. The PH of the, (log1.3=0.11) (a) 2.89 (b) (c) 3.4 (d) The buffer mixture of acetic acid and potassium acetate has PH = The ratio of [CH 3 COO ] [CH 3 COOH] in this buffer is,(log3=0.5) (PKa = 4.74) (a) 3 : 1 (b) 1 : 3 (c) 1 : 1 (d) 1 : If 50 ml of 0.2 M KOH is added to 40 ml of 0.5 M HCOOH, the PH of the resulting (dissociation constant of HCOOH is Ka) (a) -pka (b) pka (c) pka/2 (d) 2 pka 36. PH of pure water at 50 o C is... (pkw = at 50 o C) (a) 6.0 (b) 6.63 (c) 7.0 (d) How many gm of NaOH must be present in one liter of the solution to give it a ph=12 (a) 0.20 gm (b) 0.4 gm (c) 4.0 gm (d) 0.10 gm M acetic acid titrated against 0.1 M NaOH solution. What would be the difference in ph between 1/4 and 3/4 stages of neutralization of acid (b) 2 log(1/4) (d) 2 log3 Page No.: 3

4 39. The PH of solution A, B, C, D are 9.5, 2.5, 3.5 and 5.5 respectively. The most acidic (a) A (b) B (c) C (d) D 40. Which of the following solution does not act as buffer :- (a) H 3 + NaH 2 (b) Na 2 + H 2 (c) H + NH 4 (d) CH 3 COOH + CH 3 COONa 41. An acid type indicator, HIn differs in colour from its conjugate base (In - ). The human eye is sensitive to colour differences only [In ] when the ratio is greater than 10 [HIn] or smaller than 0.1. What should be minimum change in the ph of the solution to observe a complete colour change (Ka = 1.0 x 10-5 ) (a) 4 (b) 2 (c) 6 (d) 1 (42) The PH at which Mg(OH) 2 begins to precipitate from a solution containing 0.10M Mg +2 ions [KS P of Mg(OH) 2 = 1 x ] is (a) 5 (b) 9 (c) 4 (d) 10 (43) The concentration of hydroxyl ion in a solution left after mixing 100 ml of 0.1 M Mg 2 and 100 ml of 0.2 M NaOH is [KSP of Mg(OH) 2 = 1.2 x ] (1.2 x ) 1/3 = 1.4 x 10-4 (a) 2.8 x 10-3 (b) 2.8 x 10-2 (c) 2.8 x 10-4 (d) 2.8 x 10-5 (44) The volume of water needed to dissolve 1 gm of Ba (KSP = 1 x10-10 ) at 25 o C is (a) 820 liter (b) 429 liter (c) 205 liter (d) 1000 liter (45) Let the solubility of Ag in H 2 O, 0.01M Ca 2, 0.01M Na and 0.05M AgNO 3 be S 1, S 2, S 3, S 4 respectively. What is the correct relationship between there quantities (a) S 1 (b) S 1 = S 3 (c) S 1 (d) S 4 > S 1 (46) Under the same conditions which mixture by volume of 1M KOH and 1M nitric acid solution produces the highest temperature (a) (b) (c) (d) (47) At 30 o C the solubility of Ag 2 (KSP = 8 x ) would be greatest in one liter of (a) 0.05M Na 2 (b) 0.05M AgNO 3 (c) Pure water (d) 0.05M K 2 (48) KSP for Na is 36 Mol 2 Litre 2. The solubility of Na is (a) 1/36 M (b) 1/6 M (c) 6 M (d) 3600 M (49) The solubility of Ag is gm / liter. The solubility product of Ag will be (Mol.Wt. of Ag =143.5) (a) 2 x (b) 1.1 x (c) 3.1 x (d) 4.1 x (50) If the solubility of K 3 Li 3 (AlF6) 2 is 'a' mol/liter, its solubility product is equal to (a) a 2 (b) 12 a 2 (c) 18 a 3 (d) 2916 a 8 Page No.: 4

5 A N S W E R S 1. b 16. c 31. b 46. c 2. c 17. a 32. a 47. c 3. a 18. d 33. a 48. c 4. c 19. c 34. a 49. b 5. c 20. a 35. b 50. d 6. c 21. b 36. b 7. b 22. b 37. b 8. a 23. c 38. d 9. b 24. a 39. b 10. b 25. b 40. c 11. a 26. b 41. b 12. d 27. a 42. b 13. d 28. d 43. c 14. d 29. c 44. b 15. b 30. b 45. c Page No.: 5