Classes at: - Confidence building Problems

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1 PHYSICAL CHEMISTRY by: SHAILENDRA KR. Classes at: - SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna Confidence building Problems Meq. Approach 1. The radius of Bohr s first orbit in H atom is nm. The radius of second orbit in He + would be: (a) nm (b) nm (c) nm (d) The ionization potential of hydrogen atom is 13.6 ev. The energy required to remove an electron from the n = 2 state of hydrogen atom is: (a) 27.2 ev (b) 13.6 ev (c) 6.8 ev (d) 3.4 ev 3. The energy of the electron in second Bohr s orbit in the hydrogen atom is 3.41 ev. The energy of the electron in second Bohr s orbit of He + ion would be: (a) -85 ev (b) ev (c) ev (d) ev 4. The ratio of the energy of a photon of 2000 Å wavelength radiation to that of 4000 Å radiation is: (a) 1/4 (b) 1/2 (c) 2 (d) 4 5. The Bohr s energy equation for H atom reveals that the energy level of a shell is given by E = 13.58/n 2 ev. The smallest amount that an H atom will absorb if in ground state is: (a) 1.0 ev (b) 3.39 ev (c) 6.79 ev (d) ev 6. The amount of energy required to remove the electron from a Li 2+ ion in its ground state is how many times greater than the amount of energy required to remove the electron from an H atom in its ground state? (a) 9 (b) 2 (c) 3 (d) 5 7. If the ionisation potential for hydrogen atom is 13.6 ev, then the wavelength of light required for the ionisation of hydrogen atom would be: (a) 1911 nm (b) 912 nm (c) 68 nm (d) 91.2 nm 8. The ratio between kinetic energy and the total energy of the electrons of hydrogen atom according to Bohr s model is: (a) 1 : 1 (b) 1 : 1 (c) 1 : 2 (d) 2 : 1 9. The radius of second stationary orbit in Bohr s atoms in R. The radius of third orbit will be: (a) 3R (b) 9R (c) 2.25R (d) R/3 10. If the series limit of wavelength of the Lyman series for the hydrogen atom is 912 Å, then the series limit of wavelength for the Balmer series of the hydrogen atom is: (a) 912Å (b) 912 2Å (c) 912 4Å (d) 912/2Å Page No.: 1

2 11. The number of milliliter of 1M H 2 solution required to neutralize 10 ml of 1 M NaOH solution is (a) 2.5 ml (b) 5.0 ml (c) 10.0 ml (d) 20.0 ml 12. 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 solution is added to 10 cc of 3 N H 2 solution and 20 cc of 1N HCl solution. The solution will be (a) Strongly acidic (b) Alkaline (c) Neutral (d) Fairly acidic 15. The normality of 10 % acetic acid is (a) 1 N (b) 10 N (c) 1.7 N (d) 0.83 N 16. 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 into Na 3? (a) 100 cc (b) 300 cc (c) 200 cc (d) 80 cc 17. For preparation of one liter of H 2 solution we need H 2 equal to (a) 98 cm (b) 4.9 gm (c) 10 gm (d) 2.45 gm 18. 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 O 2 solution used for hair bleaching is sold as a solution of approx 5.0 gm H 2 O 2 per 100ml of solution ( Mol-wt of H 2 O 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 A N S W E R S 01. c 02. d 03. b 04. c 05. d 06. a 07. d 08. a 09. c 10. c 11. b 12. c 13. a 14. c 15. c 16. c 17. b 18. a 19. b 20. b Page No.: 2

3 PHYSICAL CHEMISTRY by: SHAILENDRA KR. Classes at: - SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna Confidence building Problems Meq. Approach 1. The number of molecules in 4.25 g of ammonia is approximately: (a) (b) (c) (d) One mole of P 4 molecules contain: (a) 1 molecules (b) 4 molecules (c) atoms (d) atoms 3. The total number of protons, electrons and neutrons in 12 g of is : (a) (b) (c) (d) The number of atoms in g of Fe (at. wt ) is: (a) twice than in 60 g carbon (b) (c) Half in 8 g He (d) The volume of 20 g of H 2 at STP is : 6. (a) 224 litre (b) 22.4 litre n C (c) 2.24 litre (d) 112 litre 6 1 mole of any gas: g g 2n (a) always occupies 1 litre (b) always occupies 22.4 litre (c) can occupy any volume at NTP (d) always occupies a fixed volume at NTP 7. The equivalent weight of H 3 in the following reaction is: H 3 + Ca(OH) 2 CaH + 2H 2 O (a) 98 (b) 49 (c) (d) g of an acid furnishes 0.5 moles of H 3 O + ions in its aqueous solution. The value of 1 g eq. of the acid will be: (a) 40 g (b) 20 g (c) 10 g (d) 100 g 9. How many moles of magnesium phosphate, Mg 3 ( ) 2 will contain 0.25 mole of oxygen atoms? (a) 0.02 (b) (c) (d) When 100 g of ethylene polymerizes to polyethylene according to the equation, nch 2 == CH 2 ( CH 2 CH 2 ) n. The weight of polyethylene produced will be: (a) (b) 100 g (c) (d) 100n g 11. A mixture containing 100 g H 2 and 100 g O 2 is ignited so that water is formed according to the reaction, 2H 2 + O 2 2H 2 O; How much water will be formed? (a) 113 g (b) 50 g (c) 25 g (d) 200 g 12. The pair of species having same percentage of carbon is: (a) CH 3 COOH and C 6 H 12 O 6 (b) CH 3 COOH and C 2 H 5 OH (c) HCOOCH 3 and C 12 H 22 O 11 (d) C 6 H 22 O 11 and C 12 H 22 O 11 Page No.: 3

4 13. Polyethylene can be produced from calcium carbide according to the following sequence of reaction; CaC 2 + H 2 O CaO + HC CH nhc CH + nh 2 ( CH 2 CH 2 ) n The mass of polyethylene which can be produced from 20.0 kg of CaC 2 is: (a) 6.75 kg (b) 7.75 kg (c) 8.75 kg (d) 9.75 kg 14. The normality of 4% (wt./vol.) NaOH is: (a) 0.1 (b) 1.0 (c) 0.05 (d) ml of concentrated H 2 (18 M) is diluted to one litre. The approximate stregth of the dilute acid is: (a) 18 M (b) 180 M (c) 0.18 M (d) 1.8 M g of hydrogen peroxide is present in 1120 ml of solution. This solution is called: (a) 10 vol solution (b) 20 vol solution (c) 30 vol solution (d) 32 vol solution 17. The volume occupied by one molecule of water (density 1 g cm 3 ) is: (a) 18 cm 3 (b) cm 3 (c) cm 3 (d) cm ml of an aqueous solution of glucose contains molecules. The concentration of solution is: (a) 0.1 M (b) 1.0 M (c) 0.2 M (d) 2.0 M 19. The percent of N in 66% pure (NH 4 ) 2 sample is: (a) 32 (b) 28 (c) 14 (d) none of these 20. The number of moles of water present in 90 g of a water is: (a) 2 (b) 3 (c) 4 (d) Weight of a single molecule of water is: (a) g (b) g (c) g (d) None of these 22. How many atoms are contained in a mole of Ca(OH) 2? (a) atom / mol (b) atom / mol (c) atom / mol (d) None of the above 23. The solution A and B are 0.1 and 0.2 molar in 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 solution is: (a) 0.15 M (b) 0.18 M (c) 0.12 M (d) 0.30 M 24. How many atoms are present in a mole of CH 3 COOC 2 H 5? (a) atom/mol (b) atom/mol (c) atom/mol (d) None of the above 25. The reaction, 2C + O 2 2CO 2 is carried out by taking 24 g carbon and 96 g O 2. Which one is limiting reagent? (a) C (b) O 2 (d) CO 2 (d) None of these 26. The weight of 350 ml of a diatomic gas at 0ºC and 2 atm pressure in 1 g. The weight of one atom is: (a) 16/N (b) 32/N (c) 16N (d) 32N (N is the av. no.) 27. In a compound C, H, N atoms are present in 9 : 1 : 3.5 by weight. Molecular weight of compound is 108, its molecular formula is: (a) C 2 H 6 N 2 (b) C 3 H 4 N (d) C 6 H 8 N 2 (d) C 9 H 12 N In a gaseous reaction of the type aa + bb cc + dd, which is wrong. (a) a litre of A combines with b litre of B to give C and D (b) a mole of A combines with b mole of B to give C and D (c) a g of A combines with b g of B to give C and D (d) a molecules of A combines with b molecules of B to give C and D 29. For the reaction, A + 2B C, 5 moles of A and 8 moles of B will produce (a) 5 moles of C (b) 4 moles of C (c) 8 moles of C (d) 13 moles of C A N S W E R S 01. b 02. d 03. a 04. a 05. a 06. d 07. b 08. a 09. b 10. b 11. a 12. a 13. c 14. b 15. c 16. a 17. d 18. d 19. c 20. d 21. a 22. b 23. c 24. a 25. a 26. a 27. c 28. c 29. b Page No.: 4

5 PHYSICAL CHEMISTRY by: SHAILENDRA KR. Classes at: - SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna Confidence building Problems Meq. Approach 1. Hydrogen ion concentration in mol/l in a solution of ph = 5.4 will be: (a) (b) (c) (d) If the dissociation constant of an acid HA is , the ph of a 0.1 M solution of the acid HA will be approximately : (a) 3 (b) 5 (c) 1 (d) 6 3. The ph of a solution is 5.0. To this solution sufficient acid is added to decrease the ph to 2.0. The increase in hydrogen ion concentration is : (a) 1000 times (b) 5/2 times (c) 100 times (d) 5 times 4. When the ph of a solution is 2. The hydrogen ion concentration is: (a) M (b) M (c) M (d) M 5. The ph of the solution obtained by mixing 10 ml of 10 1 N HCl and 10 ml of 10 1 N NaOH is: (a) 8 (b) 2 (c) 7 (d) None of these 6. Which addition would not change the ph of 10 ml of dilute hydrochloric acid? (a) 20 ml of the same dilute hydrochloric acid (b) 5 ml of pure water (c) 20 ml of pure water (d) 10 ml of concentrated hydrochloric acid 7. At 90ºC, pure water has [H 3 O + ] = 10 6 mol/litre. The value of Kw at 90ºC is: (a) 10 6 (b) (c) (d) g of NaOH present in one litre solution shows the ph: (a) 12 (b) 2 (c) 6 (d) ph of a 10 8 M solution of HCl in water is: (a) 8 (b) 8 (c) Between 7 and 8 (d) Between 6 and When 1.0 ml of dil. HCl acid is added to 100 ml of a buffer solution of ph 4.0, the ph of the solution: (a) Becomes 7 (b) Does not change (c) Becomes 2 (d) Becomes The gastric juice in our stomach contains enough hydrochloric acid to make the hydrogen ion concentration about 0.01 mol/litre. The ph of the gastric juice is: (a) 0.01 (b) 1 (c) 2 (d) A certain buffer solution contains equal concentration of X and HX. The Kb for X is The ph of the buffer is: (a) 4 (b) 7 (c) 10 (d) M HCl is diluted to 100 times. Its ph is: (a) 6.0 (b) 8.0 (c) 6.95 (d) An aqueous solution contains a substance which yields mol litre 1 ion of H 3 O +. If log 2 = , the ph of the solution is: (a) 1.5 (b) (c) 3.0 (d) The ph of 1% ionised 0.1 M, solution of a weak monoprotic acid is: (a) 1 (b) 2 (c) 3 (d) A monoprotic acid in 1.00 M solution is 0.01% ionized. The dissociation constant of this acid is: (a) (b) (c) (d) 10 5 Page No.: 5

6 ml of 2 N acetic acid mixed with 10 ml of 1N sodium acetate solution will have an approximate ph of (Ka = 10 5 ): (a) 4 (b) 5 (c) 6 (d) A monoprotic acid in 1.00 M solution is 0.001% ionized. The dissociation constant of this acid is: (a) (b) (c) (d) molar solution of formic acid is 3.2% ionized. Its ionization constant is: (a) (b) (c) (d) The ph of a M aqueous solution of HCl is slightly less than 7 because: (a) The ionization of HCl is incomplete (b) The ionization of water is negligible (c) The ionization of water at such a low concentration of HCl is significant (d) The ionization of both HCl and water are negligible 21. One litre of water contains 10 7 mole H + ions. Degree of ionization of water is: (a) % (b) % (c) % (d) % 22. pka values of four acids are given below at 25ºC. The strongest acid is: (a) 2.0 (b) 2.5 (c) 3.0 (d) The ph of a simple sodium acetate and acetic acid buffer is given by, ph = pka + log Ka of acetic acid = If [Salt] = [Acid] = 0.1 M, the ph of the solution would be about: (a) 7 (b) 4.7 (c) 5.3 (d) The ph of a 0.02 M ammonia solution which is 5% ionized will be: (a) 2 (b) 5 (c) 7 (d) Which solution will have ph closer to 1.0? (a) 100 ml of (M/10) HCl ml of (M/10) NaOH (b) 55 ml of (M/10) HCl + 45 ml of (M/10) NaOH (c) 10 ml of (M/10) HCl + 90 ml of (M/10) NaOH [Salt] 26. (d) 75 ml of (M/5) HCl + 25 ml of (M/5) NaOH [Acid] The number of mole of hydroxide [OH ] ion in 0.3 litre of M solution of Ba(OH) 2 is: (a) (b) (c) (d) A 0.01 M ammonia solution is 5% ionized. The concentration of [OH ] ion is: (a) M (b) M (c) M (d) 0.05 M g of pure NaOH is dissolved in 10 litre of distilled water. The ph of the solution is: (a) 9 (b) 10 (c) 11 (d) A certain weak acid has a dissociation constant The equilibrium constant for its reaction with a strong base is: (a) (b) (c) (d) If Ka for a weak acid is pkb value of its conjugate base is: (a) 5 (b) 6 (c) 7 (d) A buffer mixture of acetic acid and potassium acetate has ph = The ratio of [CH 3 COO ] / [CH 3 COOH] in this buffer is, (pka = 4.74): (a) 3 : 1 (b) 1 : 3 (c) 1 : 1 (d) 1 : 2 A N S W E R S 01. d 02. a 03. a 04. b 05. c 06. a 07. b 08. a 09. d 10. b 11. c 12. a 13. c 14. b 15. c 16. c 17. a 18. d 19. b 20. c 21. a 22. a 23. b 24. d 25. d 26. c 27. c 28. b 29. c 30. d 31. a Page No.: 6

7 01. Assume that the nucleus of the F atom is a sphere of radius cm. Calculate the density of matter in F nucleus. [ Ans.: g ml 1 ] 02. A metal M of atomic weight has a density of 7.42 g/cm 3. Calculate the volume occupied and the radius of the atom of this metal assuming it to be sphere. [ Ans.: radius = cm, volume = cm 3 ] g of a metal were dissolved in HNO 3 to prepare its nitrate. The nitrate was strongly heated to give 2 g oxide. Calculate equivalent weight of metal. [ Ans.: 32 ] 04. Find the milli equivalent of : PHYSICAL CHEMISTRY by: SHAILENDRA KR. Classes at: - SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna Confidence building Problems Meq. Approach (a) Ca(OH) 2 in 74 g (b) NaOH in 20 g (c) H 2 in 2.45 g [ Ans.: (a) 2000 (b) 500 (c) 50 ] 05. Find the weight of NaOH in its 50 milli equivalents. [Ans.: 2 g ] 06. Find the weight of H 2 in 1200 ml of a solution of 0.2 N strenght. [Ans.: g] 07. Calculate the amount of calcium oxide required when it reacts with 852 g of P 4 O 10.[ IIT 2005] [ Ans.: 1008 g ] 08. What weight of Na 2 CO 3 of 95% purity would be required to neutralize 45.6 ml of N acid. [Ans.: g ] 09. How many millilitre of 0.5 M H 2 are needed to dissolve 0.5 g of copper II carbonate? [ IIT 1999] [Ans.: V = ml ] 10. What is the strength in g per litre of a solution of H 2, 12 ml of which neutralized 15 ml of N/10 NaOH solution? [Ans.: g/litre] 11. The formula weight of an acid is cm 3 of a solution of this acid containing 39.0 g of the acid per litre were completely neutralized by 95.0 cm 3 of aqueous NaOH containing 40.0 g of NaOH per litre. What is the basicity of the acid? [ROORKEE 2000] [Ans.: Acid is dibasic] Page No.: 7

8 12. Calculate the normality of the resulting solution made by adding 2 drops (0.1 ml) of 0.1 N H 2 in 1 litre of distilled water. [ Ans.: N = 10 5 ] 13. What volume at NTP of ammonia gas will be required to be passed into 30 ml of N H 2 solution to bring down the acid normality to 0.2 N? [UPSEAT 1991] [Ans.: ml] 14. Two litre of NH 3 at 30ºC and 0.20 atmosphere is neutralized by 134 ml of a solution of H 2. Calculate normality of H 2. [Ans.: N = 0.12 ] 15. Calculate normality of mixture obtained by mixing: (a) 100 ml of 0.1 N HCl + 50 ml of 0.25 N NaOH (b) 100 ml of 0.2 M H ml of 0.2 M HCl (c) 100 ml of 0.2 M H ml of 0.2 M NaOH (d) 1 g equivalent of NaOH ml of 0.1 N HCl [Ans.: (a) , (b) 0.267, (c) 0.1, (d) 9.9 ] 16. Calculate the amount of KOH required to neutralize 15 Meq. of the following: (a) HCl (b) KH (c) N 2 O 5 (d) CO 2. [ Ans.: (a) 0.84 g (b) 0.84 g (c) 0.84 g (d) 0.84 g] 17. What volume of water is required to make 0.20 N solution from 1600 ml of N solution? [Ans.: 40 ml ] 18. What volume of a solution of hydrochloric acid containing 73 g of acid per litre would suffice for the exact neutralization of sodium hydroxide obtained by allowing 0.46 g of metallic sodium to act upon water? [UPSEAT 1997] [ Ans.: V = 10 ml ] 19. Find out equivalent weight of H 3 in the reaction Ca(OH) 2 + H 3 CaH + 2H 2 O [ Ans.: 49 ] 20. What volume of 0.20 M H 2 is required to produce 34.0 g of H 2 S by the reaction? 8KI + 5H 2 4K 2 + 4I 2 + H 2 S + 4H 2 O [ Ans.: V = 25 L ] Page No.: 8