"Enm
By: Er. Arvind Tripathi (B.Tech, IT-BHU), Momentum, Gorakhpur Ionisation constant of a weak acid (fi-4) in terms ofand Am is
rA®5 CA2
(b) "
1.
A *
(a) Ka =
(c) K„=-A : , ( A : , - A J
Ka =
a:<A:-A„,)
(d) None of these.
2. The potential of a Ag/AgCI electrode measured with respect to a saturated calomel electrode is-0.022 V. What is the value of the standard reduction potential for the Ag/AgCI electrode.
[Given : Hg2Cl2 + 2e -> 2Hg(.s) + 2 C P (sat. KC1);
E° = 0.244 V]
(a) 0.266 V (b) - 0.266 V (c) - 0.222V (d) 0.222 V.
3. Ag ,Ag- (1M)|| Ag+ (2M)| Ag
1L solution 1 L solution
0.5 F of electricity in the LHS (anode) and IF of electricity in the RHS (cathode) is first passed making them independent electrolytic cells at 298 K. EMF of the cell after electrolysis will be
(a) increased (b) decreased
(c) no change (d) time is also required.
4. Cost of electricity for the production of xL H2 at NTP at cathode is Rs. x, then cost of electricity for the production of xh 02 gas at NTP at anode will be (assume
1 mol of electrons as one unit of electricity)
(a) 2x (b) 4x (c) 16A- (d) 32x.
5. For the following cell reaction
Pb (5) + Hg2S04 (j) ->> PbS04 + 2Hg (/) E = 0.92 V K,„ (PbS04) = 2 x io-8, Kw (Hg2S04) = 1 x 10"6
Hence, E is
(a) 0.92 V (b) 0.89 V (c) 1.04 V (b) 0.95 V 6. The wavelengths of two photons are 2000 A and 4000A respectively. What is the ratio of their energies?
(a) 1/4 (b) 4 (c) 1/2 (d) 2.
7. Benzoic ,-idd solution is titrated with NaOH conducto-metricaly, graphical representation of the titration is :
(a) (b)
N a O H N a O H
(c) O (d) o
N a O H N a O H
8. An electron, a proton and an alpha particle have kinetic energies of 16£, 4E and E respectively.- What is the qualitative order of their de Broglie wavelengths ? (a) K >Xp = Xa (b) Xp = Xa> Xe
(c) Xp>Xe>Xa (d) Xa<Xe»Xp
9. The nucleus of an atom is located at x = y = z = 0.
If the probability of finding an .y-orbital electron in a tiny volume around x = a, ^ = z = 0 i s l x IO^5, what is the probability of finding the electron in the same sized volume around x = z = 0, y = a?
(a) 1 x 10~5 (b) 1 x io-5 x a
(c) 1 x io 5 x a2 (d) 1 x 10~5 x a~]
10. Suppose a particle has four quantum numbers such that permitted value are : n : 1, 2, 3
I : ( « — ! ) , ( « — 3), (n — 5) but no negative number J
<4M4
the latter is not negativem : - / in integral steps to + /
What are other permitted values for n =
(a)
(c) 2 — m 1 1
2 2
2 " + 2
t J (b)
(d)
1
in
' 2 "+2
0 —
-'38 CHEMISTRY TODAY | OCTOBER '05
11. When the value of azimuthal quantum number is 3, the maximum and the minimum values of spin multiplicities are
(a) 4, 3 (b) 8, 1 (c) 1, 3 (d) 8, 2 12. The radii of two of the first four Bohr orbits of the hydrogen atom are in the ratio 1: 4. The energy difference between them may be :
(a) either 12.09 eV or 3.4 eV (b) either 2.55 eV or 10.2 eV (c) either 13.6 eV or 3.4 eV (d) either 3.4 eV or 0.85 eV
13. Equilibrium is established by introducing an equal number of moles of N2 and H2 into a 1-L flask. At equilibrium, which of the following statements is/are true?
( b ) [HJ < [NJ [H2] = [NH3] in
; n t
log S
VT-(a) [H2]>[N2]
(c) [H2] > [NH3] (-14. Solubility (S) of a solu*
a solvent (say H20) is depen on temperature as given by
S = Ae^'KT
where AH is he; ^f reaction solute + HzO —> solution 1 ' ± x For a given solution va . of
log S with temp, is shown rraphically. Hence, solute is (a) CuS04 • 5H20 (b) NaCl
(c) Sucrose (d) CaO 15. Before equilibrium is set up for the chemical reaction N204 —>2N02, vapour density d of the gaseous mixture was measured. If D is the theoretical value of vapour density, variation of with Did is by the graph.
What is value of D/d at point A?
(a) 0 (b) 0.5 (c) 16. For the equilibrium
LiC1.3NH3 (s) -> LiCl.NH3 <» + 2NH3
Kp = 9 atm2, at 40°C a 5 litre contains 0.1 mole of LiCl.NH3. How many moles of NH3 should be added to the flask at the temperature to drive the backward reaction for completion.
(a) 0.7837 moles (b) 0.8837 moles (c) 0.9837 moles (d) 1.0837 moles
17. 40% of a mixture of 0.2 mole of N2 and 0.6 mole of H2 react to give NH3 according to the equation, (g) + 3 H2(g) —> 2NH3 (g) at constant temperature and pressure.
Then the ratio of the final volume to the initial volume of gases is
as-1
D/d-(d) 1.5
(a) 4:5 (b) 5:4 (c) 7:10 (d) 8:5 18. CuS04 5H20 CuSO4.3H2O0) + 2H20 (g), Kp for this equilibrium is 1.086 * 1 a t m2 at 25°C. What is the maximum pressure of water vapour (moisture) in the atmosphere, below which the pentahydrate is efflorescent?
(a) 7.92 mm (b) 8.21 mm (c) 6.68 mm (d) 5.69 mm
19. Which of the following buffers containing NH4OH and NH4C1 has the highest pH value?
conc. of NH4OH(mol L"1) conc. ofNH4Cl (mol L"1) (a) 0.50 (a) 0.50
(b) 0.10 (b) 0.50 (c) 0.50 (c) 1.50 (d) 0.50 (b) 1.10
20. In an experiment to determine the enthalpy of neutralization of sodium hydroxide with sulphuric acid, 50 cm3 of 0.4 M sodium hydroxide were titrated thermometrically with 0.25 M sulphuric acid. Which of the following plots gives the correct representation?
(a) (b)
10 30 50 Vol. of H,SO„
!0 30 50 Vol. of H,SO,
(C) (d)
10 30 50 Vol. of H,SO,
J 1 L 10 30 50 Vol. of H,SO,
21. In an aqueous solution of 1 M NH4HS the expression for [H+] will be
(a) + ] =
( b ) [ H+] = X . -K„
(c) [H+] = j A 'a, | ^ + A', (d) None of these.
22. Consider the
23. Consider the following graph pertaining to distillation. The
blue colour formation in side X blue colour formation in side Y
blue colour formation in both of the side X and Y no blue colour formation
(b)
(c)
24.
with K4 [Fe(CN)s] in aq.
solution gives blue colour.
These are separated by a semipermeable membrane a vessel and after reaction, H20 is added. Aqueous solution required 1 mol of HCl. Mol fraction of H2 in the mixture after reaction is
(a) 1/6 (b) 5/6
(c) 1/3 (d) none of these.
26. 50.0 mL of a gaseous mixture of H, and HCl is exposed to a sodium amalgam, the volume decreases to 42.5 mL. If 100.0 mL of the same mixture is added to 50.0 mL to gaseous ammonia and then exposed to water, what will be the volume of the final mixture ? (a) 35.0 mL (b) 50.0 mL (c) 15.0 mL (d) 70.0 mL
27. A mixture of Na2C204 (A) and KHC204. H2C204. (B) required equal volumes of 0.1 M KMn04 and 0.1 M NaOH separately. Molar ratio of A and B in the mixture is
— - Detailed solutions will be published in next issue.
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CHEMISTRY TODAY | OCTOBER '05