Here are the question of complete physical Chemistry -
Solve these to strongen the concepts
01. In the formation of sulphur trioxide by contact process, 2SO2 + O2 2SO3, the rate of reaction was measured as = 3.2 × 10-4 g lit-1 sec-1. the rate of reaction expressed in terms of SO3 will be-
(A) 1.25 × 10-4 mol L–2 sec-1 (B) 50 × 10-4 mol L–1 sec–1
(C) 3.75 × 10-4 mol L–1 sec-1 (D) 1.6 × 10-3 mol L–1 sec–1
(A) 1.25 × 10-4 mol L–2 sec-1 (B) 50 × 10-4 mol L–1 sec–1
(C) 3.75 × 10-4 mol L–1 sec-1 (D) 1.6 × 10-3 mol L–1 sec–1
02. Consider a reaction aG + bH Products. When concentration of both the reactants G and H is doubled, the rate increases by eight times. However, when concentration of G is doubled keeping the concentration of H fixed, the rate is doubled. The overall order of the reaction is –
(A) 0 (B) 1
(C) 2 (D) 3
03. The activation energies of two reactions are ,if the rate of first reaction increases by 20% and that of second reaction increases by 40% on increasing temperature from 25°C to 30°C than which of the following is correct?
04. For a Ist order reaction nA B whose concentration Vs time curve as shown below If half life for the reaction is 24 mins the value of n is
(A)1 (B) 2
(C) 3 (D) 4
05. The rate constant of a first order reaction is 10–3 min–1 at 300 K. The temperature coefficient of the reaction is 2. What is the rate constant of the reaction at 350 K approximately ?
(A) 16 × 10–3 (B) 64 × 10–3
(C) 32 × 10–3 (D) 250
06. The reaction , is started with initial pressure of N2O5 (g) equal to 600 torr. What fraction of N2O5 (g) decomposed when total pressure of the system is 960 torr ?
(A) 0.05 (B) 0.1
(C) 0.2 (D) 0.4
07. The rate constant (k) of one reaction is double of the rate constant (k) of another reaction. Then the relationship between the corresponding activation energies of the two reactions (Ea and Ea) will be -
(A) Ea > Ea (B) Ea = Ea
(C) Ea < Ea (D) Ea = 4Ea
08. For a first order reaction, the plot of ‘t’ against log C gives a straight line with slope equal to –
(A) (k/2.303) (B) (–k/2.303)
(C) (ln k/2.303) (D) – k
09. The distribution of molecular kinetic energy at two temperature is as shown in the following graph. Which of the following conclusions are correct–
(A)The number of molecules with energy Ea or greater is proportional to the shaded area for each temperature
(B)The number of molecules with energy Ea or less is proportional to the shaded area for each temperature
(C)The number of molecules with energy Ea is the mean of all temperatures
(D)The graph is not according to the Maxwell-Boltzmann energy distribution law
10. The reaction, X + 2Y + Z N occurs by the following mechanism (i) X + Y M (very rapid equilibrium) (ii) M + Z O (slow) (iii) O + Y N (very fast) What is the rate law for this reaction -
(A) Rate = k[Z] (B) Rate = k[X] [Y]2 [Z]
(C) Rate = k[N] (D) Rate = k [X] [Y] [Z]
11. For the first-order decomposition of N2O5 (g) written as 2 N2O5 (g) 4 NO2 (g) + O2 (g) rate = K [N2O5] N2O5 (g) 2 NO2 (g) + O2 (g) rate = K [N2O5] Which of the following relation is correct ?
(A) K = K (B) K > K
(C) K > 2K (D) 2K = K
12. Time taken for completion of 20% of a reaction becomes half when initial concentration of reactants are made double. The order of reaction will be
(A) 1 (B) 2
(C) 0 (D) 3
13. Under the same reaction conditions, initial concentration of 1.386 mol dm–3 of a substance becomes half in 40 seconds and 20 seconds through first order and zero order kinetics, respectively. Ratio of the rate constants for first order (k1) and zero order (k0) of the reactions is
(A) 0.5 mol–1 dm3 (B) 1.0 mol dm–3
(C) 1.5 mol dm–3 (D) 2.0 mol–1 dm3
14. Reaction : 2Br¯ + H2O2 + 2H+ Br2 + 2H2O take place in two steps : The order of the reaction is –
(A) 3 (B) 6
(C) 5 (D) 0
15. 99% of a first order reaction was completed in 32 min. When will 99.9% of the reaction complete –
(A) 50 Min (B) 46 Min
(C) 49 Min (D) 48 Min
16. For a first order reaction, (A) products, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M,is
(A) 3.47 × 10–5 M/min (B) 1.73 × 10–4 M/min
(C) 1.73 × 10–5 M/min (D) 3.47 × 10–4 M/min
(A) 3.47 × 10–5 M/min (B) 1.73 × 10–4 M/min
(C) 1.73 × 10–5 M/min (D) 3.47 × 10–4 M/min
17. Two reactions R1 and R2 have identical pre-exponential factors. Activation energy of R1 exceeds that of R2 by 10 kJ mol–1. If k1 and k2 are rate constants for reactions R1 and R2 respectively at 300 K, then ln (k2/k1) is equal to : (R = 8.314 J mol–1 K–1)
(A)12 (B) 6
(C) 4 (D) 8
18. At 518°C, the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of 363 Torr, was 1.00 Torr s–1 when 5% has reacted and 0.5 Torr s–1 when 33% had reacted. The order of the reaction is :
(A) 1 (B) 0
(C) 2 (D) 3
19. The inversion of cane sugar proceeds with half life of 500 minute at pH = 5 for any concentration of sugar. However if pH = 6, the half life changes to 50 minute. The rate law expression for sugar inversion can be written as :
(A) r = K [sugar]2 [H+]0 (B) r = K [sugar]1 [H+]0
(C) r = K [sugar]1 [H+]1 (D) r = K [sugar]0 [H+]1
20. According to the Arrhenius equation, which of the following is incorrect-
(A)a high activation energy usually implies a fast reaction
(B)rate constant increases with increase in temperature, This is due to a greater number of collisions whose energy exceeds the activation energy.
(C)higher the magnitude of activation energy, stronger is the temperature dependence of the rate constant.
(D)the pre-exponential factor is a measure of the rate at which collisions occur, irrespective of their energy. ELECTROCHEMISTRY PERCENTAGE WEIGHTAGE- 3.67%
21. For which of the following cells EMF remains constant for a long interval of time
(A) Daniel Cell (B) Fuel Cell
(C) Mercury Cell (D) Nickel Cadmium Cell
22. The potential of hydrogen electrode in contact with a solution whose pH is 6, pressure of H2 is 1 bar will be –
(A) 0.36 V (B) 0.72V
(C) 0.3V (D) 0.21V
23. The magnitude of standard reduction potentials of two metals 'X' and 'Y' are Y2+ + 2e– Y |E1| = 0.34V X2+ + 2e– X |E2| = 0.25V When two half cells of X and Y are connected to construct a galvanic cell, electrons flow in the external circuit from X to Y. When X is connected to a standard SHE, electrons flow in the external circuit from X to SHE. If a half cell X2+ (0.1M) | X is connected to another half cell Y2+ (1.0 M) | Y to construct a galvanic cell at 25ºC, the EMF of cell is-
(A) 0.62 V (B) 0.72V
(C) 0.3V (D) 0.21V
24. When equal number of coulomb of electricity is passed through aqueous solution of AX and BX2 and if number of moles of A and B deposited respectively are Y and Z then -
(A) Y = Z (B) Y < Z
(C) Z = 2Y (D) Y = 2Z
25. For the cell prepared from electrode A and B. Electrode A : Cr2O72–/Cr3+, E0red = + 1.33 V and Electrode B : Fe3+/Fe2+, E0red = 0.77 V Which of the following statements is not correct
(A)The electrons will flow from B to A when connection are made
(B)The emf of the cell will be 0.56 V
(C)A will be positive electrode (D)None of these
26. The EMF of the cell M | Mn+ (0.01M) || H+ (1M) | H2(g) (1 atm), Pt at 25°C is 0.82V. Calculate the valency of the metal if the standard oxidation potential of the metal is 0.76V.
(A) 3 (B) 2
(C) 4 (D) 5
27. Aqueous solution of NaBr Products The products may be -
(A) Na, O2 (B) H2, O2
(C) H2, O2, NaOH (D) H2, Br2, NaOH
28. In a conductivity cell the two platinum electrodes, each of area 10 sq. cm are fixed 1.5 cm apart. The cell contained 0.05 N solution of a salt. If the two electrodes are just half dipped into the solution which has a resistance of 50W, find equivalent conductance of the salt solution –
(A) 120 S cm2 eq–1 (B) 160 S cm2 eq–1
(C) 120 S m2 eq–1 (D) 125 S cm2 eq–1
29. The specific conductivity of a saturated solution of AgCl is 3.40 × 10–6 ohm–1 cm–1 at 25ºC. If ohm–1 cm2 mol–1 & lCl– = 67.7 ohm–1 cm2 mol–1 , the solubility of AgCl at 25ºC is -
(A) 2.6 × 10–5 mol L–1 (B) 3.731 × 10–3 mol L–1
(C) 3.731 × 10–5 moL–1 (D) 2.6 × 10–3 gL–1
30. He standard reduction potentials at 298 K for the following half-reactions are given against each. Zn2+ (aq) + 2e Zn (s) ; – 0.762 Cr3+ (aq) + 3e Cr (s) ; – 0.74 V 2H+ + 2e H2 (g) ; ± 0.0 V Fe3+ (aq) + e Fe2+ (aq); + 0.77 V Which is the strongest oxidising agent ?
(A) Zn (s) (B) Cr (s)
(C) H2 (g) (D) Fe3+ (aq)
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