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Physical chemistry dr. R K gupts test 02

Page No 2933. PCl5 is 40% dissociated when pressure is 2 atm. It will be 80 % dissociated

when pressure is approximately:

a. 0.2 atm b. 0.5 atm c. 0.3 atm d. 0.6 atm [a]

7. In the following equilibriumFe3+

(aq) + SCN-(aq) Fe(NCS)

2+(aq)

pale yellow colourless

Red colour gets darker if we add

a. aqueous FeCl3 solution b. aqueous KCNS solution

c. any of the above d. none of the above [c]

10. For the reaction

NH2COONH4 (s) 2NH3 (g) + CO2(g)

the equilibrium constant Kp = 2.92 x 10-5 atm3. The total pressure of the gaseous

products when 1 mol of reactant is heated will be:

a. 0.0194 atm b. 0.0388 atmc. 0.0582 atm d. 0.0667 atm [c]

22. For the equilibrium

Ag+ + 2NH3 Ag(NH3)2+ K1 = 1.8 x 10

7

and Ag+

+ Cl-AgCl K2 = 5.6 x 109

Hence, for the equilibrium

AgCl + 2NH3 Ag(NH3)2+

+ Cl-

Equilibrium constant is :

a. 0.32 x 10-2 b. 0.31 x 10-21

c. 1.01 x 107 d. 1.01 x 10-17 [a]

30. For the following equilibria relation between Kc and Kx is:

2SO2(g) + O2(g) 2SO3(g). Kx is the mole friction equilibrium constant.

a. Kc = Kx (RT)-1

b. Kc = Kx(RT)

c. Kc = Kx (1/V) d. Kc = Kx (V) [d]

Page 302. 3. At constant temperature, the equilibrium constant (Kp) for the

decomposition reaction, N2O4 2NO2, is expressed by Kp =

() where P =

pressure, x = extent of decomposition. Which one of the following statements is

true?

a. Kp increases with increase of P

b. Kp increases with increase of x

c. Kp increases with decrease of x [d]

d. Kp remains constant with change in P and x

Page No 345

. 23. Given the following reaction

I. N2(g) + 2O2(g)2NO2 g, 16.18 kcal

II. N2(g) + O2(g)N2O4(g), = 2.31 kcalBased on the above facts:

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a. NO2 is more stable than N2O4 at low temperature.

b. N2O4 is more stable than NO2 at low temperature

c. both are equally stable at low temperature

d. none of the above [b]

25. When one mole of an ideal gas is compressed to half its initial volume and

simultaneously heated to twice its initial temperature, the change in entropy () is.

a. CV In 2 b. CP In 2 c. R In 2 d. (CV R) In 2[d]

32. What are the signs of the entropy change (+ or

) in the following:I. A liquid crystallises into a solid

II. Temperature of a crystalline solid is raised from 0 K to 115 K

III. 2NaHCO3 (s) Na2CO3(s) + CO2(g) + H2O(g)

IV. H2(g) 2H(g)

I II III IV I II III IV

a. - + + + b. - - - +

c. + + + - d. + - - -

[a]

40. For the reaction

Ag2CO3(s) 2Ag+

(aq) + CO32-

(aq)

= + 6.3 kJ. Hence thermodynamic equilibrium constant at 25 C is

a. 3.2 x 10-26

b. 63.3 x 103

c. 8.06 x 10-12

d. 1.2 x 10-12

[c]

57. For a particular reaction = - 38.3 kJ and = - 113 JK-1. This reaction is:

a. Spontaneous at all temperatures

b. Non- spontaneous at all temperatures

c. Spontaneous at a temperatures below 338 K

d. Spontaneous at a temperatures above 339 K [c]

Page No 382

2 The standard heat of combustion of propane is 2220.1kJ mol-1. The standard

heat of vaporisation of liquid water is 44.0kJ mol-1

. What is of

C3H8(g) + 502(g) 3CO2(g) + 4H2O(g)?

a. 2220.1 kJ b. 2044.1 kJ c. 2396.1 kJ d. 2176.1 kJ [b]

3 The gas absorbs 100 J heat and is simultaneously compressed by a constant

external pressure of 1.50atm from 8 L to 2 L in volume. Hence, will be

a.

812 J b. 812 J c. 1011 J d. 911 J [c]9. H2S(g) HS(g) +H(g), = x1

[H2S(g)] = x2, [H(g)] = x3 [a]

hence, (HS) is

a. x1 + x2 x3 b. x3 x1 x2 c. x1 x2 x3 d. x3 x1 + x2

12. H2(g) + O2 (g) H2O()

BE (H H) = x1 ; BE (O = O) = x2; BE (O H)= x3

Latent heat of vaporisation of water liquid into water vapour = x 4 then

(heat of formation of liquid water) is:

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a. x1 + x2/2 x3 + x4 b. 2x3 x1 x2/2 x4

c. x1 + x2/2 2x3 x4 d. x1 + x2/2 2 x3 + x4 [c]

15 Given, Na(s) Na(g)

Na(g) Na+(g) + e-

Cl2(g) 2Cl(g)

Cl(g) + e- Cl-(g)

Na+(g)+Cl

-(g)

NaCl(s)

[letters above arrow () are energy parameters], of NaCl is.

a. S + I +D E U

b. S + I + D/2 + E + U

c. S + I + D/2 E U [c]

d. S + I + D/2 E + U

36. of CH4, C2H6 and C3H8 are 210, 368.4 and 526.3 kcal mol-1.

Hence,

of C4H10 is approximately:

a. 684.0 kcal b. 368.4 kcal c. 842.0 kcal d. 600.0 kcal [a]

Page No 389

2. Which of the reaction defines

a. C(diamond) + O2(g) CO2(g)

b. H2(g) + F2(g) HF(g)

c. N2(g) + 3H2(g) 2NH3(g)

d. CO(g) + O2(g) CO2(g) [b]

Page No 446

5. Autoionisattion of liquid NH3 is

2NH3 NH4+ + NH2-with = [NH4

+ ] [NH2-] = 10-30 at 50 C

Number of amide ions NH2-, present per mm3 of pure liquid NH3 is

a. 600 b. 300 c. 200 d. 100 [a]

7. pH of the solution containing 50.0 mL of 0.3M HCl and 50 mL of 0.4 M NH3 is

[pKa(NH4+) = 9.26]

a. 4.78 b. 9.26 c. 8.78 d. 4.63 [c]

24. To prepare a buffer of pH 8.26, amount of (NH4)2 SO4 to be added into 500 mL

of 0.01 M NH4OH solution [pKa(NH4+) = 9.26]

a.0.05 mole b. 0.025 mole c. 0.10 mole d. 0.005 mole [b]

29. If the equilibrium constant of the reaction of weak acid HA with strong base is

109, then pH of 0.1 M NaA is

a. 5 b. 9 c. 7 d. 8 [b]

44. Ksp of CaSO4 is 4 x 10-12. CaSO4 is precipitated on mixing equal volumes of the

following solution :

a. 3 x 10-6

M CaCl2 and 3 x 10-6

M (NH4)2 SO4

b.4 x 10-6 M CaCl2 and 3 x 10-6 M (NH4)2 SO4

c.6 x 10-6 M CaCl2 and 3 x 10-6 M (NH4)2 SO4

d.In all cases [c]

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52. Some chemists at ISRO wished to prepare a saturated solution of a silver

compound and they wanted it to have the highest concentration of silver ion

possible. Which of the following compounds would they use?

Ksp(AgCl) = 1.8 x 10-10

,Ksp (AgBr) = 5.0 x 10-13

,

Ksp(Ag2CrO4) = 2.4 x 10-12

[c]

a. AgCl b. AgBr c. Ag2CrO4 d. Any of these

70. pKb of CH3COO- ion is 9.26. pH of solution when 0.01 M CH3 COOH is

neutralised 50 % and at equivalence point using 0.01 M NaOH are respectively:a. 4.63, 8.22 b. 4.74, 8.22 c. 2.37, 4.11 d. 474, 8.37 [b]

27. Which of the following molecules have all the bonds equal in length?

1.PCl5 2. SF4 3. SiF4 4. NCl3

a. 1 & 2 b. 1, 2 & 3 c. 3 & 4 d. 2 ,3 & 4[c]

30. Match the compounds with shape on the right

Column I Column II

x. XeO2F2 p. Seesaw

y. I3- q. Square Pyramid

z. BrF5 r. Trigonal Pyramid

t. SO32-

s. Linear

x y z t x y z t

a. p q r s b. p s q r

c. r s p q d. q p s r [b]

Page No 452

49. The hybridization of each carbon in the molecule in the ordermarked is

a. All sp2

b. 1 ,2 ,3 ,4 sp2, 5, 6 sp3

c. 1, 3 ,sp2

2 ,4, 5, 6- sp3

d. 1, 2 ,3sp2 4, 5 ,6 sp3 [b]

62. The molecule that may be destabilized by adding an electron is

a. Nitrogen b. H2+

c. CN d. C2 [a]

102. The correct order of melting points of CaCl2, SrCl2 and BaCl2 can be given as

a. Cacl2 < BaCl2 < SrCl2 b. CaCl2 < SrCl2 < BaCl2

c.CaCl2 < SrCl2 BaCl2 d. BaCl2 < SrCl2 < CaCl2 [b]