Title 03. ELECTROCHEMISTRY.pdf ✅

PAPER 1 (1.) Find the charge in coulomb on 1 g -ion of 3 N − : (1) 5 1.89 10  coulomb (2) 5 2.89 10  coulomb (3) 3 3.89 10  coulomb (4) 2 4.89 10  coulomb (2.) Calculate the electrode potential at a copper electrode dipped in a 0.1M solution of copper sulphate at 25 C . The standard electrode potential of 2 Cu / Cu + system is 0.34 volt at 298 K. (1) 0.31045 volt (2) 0.20045 volt (3) 0.11045 volt (4) 1.21045 volt (3.) The standard oxidation potential of zinc is 0.76 volt and of silver is −0.80 volt. Calculate the emf of the cell : ( 3 3 )2 Zn Zn NO AgNO Ag0.25M 0.1M at 25 C : (1) 0.5187 volt (2) 1.5187 volt (3) 2.5187 volt (4) 3.5187 volt (4.) Calculate the emf of the following cell at 25 C : 2 2 2 atm 10 atm Pt H HCl H ,Pt (1) -0.0206 volt (2) +0.1206 volt (3) -1.0206 volt (4) +1.0206 volt (5.) The standard reduction potentials of 2 Cu Cu + ∣ and 2 Cu Cu + + ∣ are 0.337 V and 0.153 V respectively. The standard electode potential of Cu Cu + ∣ half cell is : (1) 0.184 V (2) 0.827 V (3) 0.521 V (4) 0.490 V (6.) Exactly 0.4 faraday electric charge is passed through two electolytic cells in series, first containing AgNO3 and second CuSO4 solution. How many gram of each metal will be deposited assuming only cathodic reaction in each cell respectively : (1) 43.2 g,12.7 g (2) 13.2 g,12.7 g (3) 12.2 g,15.7 g (4) 23.2 g,22.7 g (7.) During the electrolysis of brine (NaCl) solution, what volume of chlorine gas, at STP is produced in the same time, in which 5.0 litre of hydrogen gas is liberated under the same condition : (1) 2.5 lit (2) 5.0 lit (3) 7.5 lit (4) 10.0 lit (8.) Given that 3 2 Fe Fe Fe Fe E 0.036 V,E 0.439 V + + = − = − ∣ ∣ , the value of standard electrode potental for the change ( ) ( ) 3 2 aq aq Fe e Fe + + + → will be : (1) 0.770 V (2) −0.270 V (3) −0.072 V (4) 0.385 V (9.) Electrolysis of dilute aqueous NaCl solution was carried out by passing 10 milliampere current. The time required to liberate 224ml (S.T.P) of H2 gas at the cathode is : (1) 4 9.65 10 s  (2) 4 19.3 10 s  (3) 4 28.95 10 s  (4) 4 38.6 10 s 
(10.) When during electrolysis of a solution of AgNO3 , 9650C of charge pass through the electroplating bath, the mass of silver deposited on the cathode will be : (1) 1.08 g (2) 10.8 g (3) 21.6 g (4) 108 g (11.) For a cell reaction involving a two-electron change, the standard emf of the cell is found to be 0.295 V at 25 C . The equilibrium constant of the reaction at 25 C will be: (1) 10 1 10−  (2) 2 29.5 10−  (3) 10 (4) 10 1 10  (12.) 1 2 E E, and E3 are the e.m.f. values of the three galvanic cells respectively : i. ( ) ( ) 2 2 Zn Zn 1M Cu 0.1M Cu + + ii. ( ) ( ) 2 2 Zn Zn 1M Cu 1M Cu + + iii. ( ) ( ) 2 2 Zn Zn 0.1M Cu 1M Cu + + Which one of the following is true : (1) E E E 2 3 1   (2) E E E 3 2 1   (3) E E E 1 2 3   (4) E E E 1 3 2   (13.) Find the weight ratio of W : W H O 2 2 by electrolysis of H O2 by passing 4F electricity : (1) W : W 1:8 H O 2 2 = (2) W : W 1: 2 H O 2 2 = (3) W : W 2 :1 H O 2 2 = (4) W : W 8 :1 H O 2 2 = (14.) 12.3 g nitrobenzene is reduced into aniline by electrolysis, if current efficiency is 25% calculate charge reduced in coulombs : (1) 12 96500  coulombs (2) 1.2 9650  coulombs (3) 24 9650  coulombs (4) 96500 coulombs (15.) Find the product of electrolysis at anode and at cathode evolve due to electrolysis of aquous NaCl respectively: (1) H2 gas at cathode, O2 gas at anode (2) H2 gas at cathode, Cl2 gas at anode (3) H2 gas at anode, Cl2 gas at cathode (4) H2 gas at anode, O2 gas at cathode (16.) Using the data given below find out in which option the order of reducing power is correct : 2 3 2 7 2 2 3 4 E Cr O / Cr 1.33 V,E Cl / Cl 1.36 V, E MnO /Mn 1.51 V,E Cr / Cr 0.74 V − + − + + = = − = = − (1) 3 2 Cr Cl Mn Cr + − +    (2) Mn Cl Cr Cr 2 3 + − +    (3) 3 2 Cr Cl Cr O MnO 2 7 4 + − − −    (4) Mn Cr Cl Cr 2 3 + + −    (17.) For the given cell Mg Mg Cu Cu 2 2 + + (1) Cu is the oxidising agent (2) Cu is cathode
(3) The cell reaction is Mg Cu Mg Cu 2 2 + + + → + (4) Both 2 and 3 option are correct (18.) The conductivity of 0.2M solution of KCl at 298 K is 1 0.0248 S cm− . Calculate its molar conductivity: (1) 2 1 120 S cm mol− (2) 2 1 134 S cm mol− (3) 2 1 124 S cm mol− (4) 2 1 145 S cm mol− (19.) A 5A current is passed through a solution of zinc sulphate for 40min . The amount of zinc deposited at the cathode is : (1) 40.65 g (2) 0.4065 g (3) 4.065 g (4) 65.04 g (20.) The equivalent conductance of M / 32 solution of a weak monobasic acid is 2 8.0mhocm and at infinite dilutin is 2 400mhocm . The dissociation constant of this acid is : (1) 5 1.25 10−  (2) 6 1.25 10−  (3) 4 6.25 10−  (4) 4 1.25 10−  (21.) The equivalent conductances of sodium chloride, hydrochloric acid and sodium acetate at infinite dilution are 126.45, 426.16 and 1 2 91.0ohm cm − equiv −1 , respectively, at 25 C . Calculate the equivalent conductance of acetic acid at infinite dilution : (1) 1 2 190.7ohm cm − equiv −1 (2) 1 2 290.7ohm cm − equiv −1 (3) 1 2 390.7ohm cm − equiv −1 (4) 1 2 490.7ohm cm − equiv −1 (22.) If the 0 Ecell for a given reaction has a negative value, then which of the following gives the correct relationships for the values of 0 ΔG and Keq. : (1) 0 ΔG 0;K 1   eq (2) 0 ΔG 0;K 1   eq (3) 0 ΔG 0;K 1 eq (4) 0 ΔG 0;K 1   eq (23.) Equivalent conductance of NaCl, HCl and C H COONa 2 5 at infinite dilution are 126.45, 426.16 and 1 2 91ohm cm − , respectively. The equivalent conductance of C H COOH 2 5 is : (1) 1 2 201.28ohm cm − (2) 1 2 390.71ohm cm − (3) 1 2 698.28ohm cm − (4) 1 2 540.48ohm cm − (24.) The unit of molar conductance is : (1) 1 2 1 ohm cm mol − − (2) 2 1 mhocm mol− (3) simen 2 1 cm mol− (4) All of these (25.) Calculate equivalent conductance of 2 4 1 mole SO solution whose conductivity 1 1 0.26ohm cm − − . If the volume of solution is 1 lit.:
(1) 110 (2) 120 (3) 130 (4) 140 (26.) The conductivity of 0.25M solution of a weak electrolyte xy is 1 0.0125 S cm− . Λm  of the electrolyte is 2 1 500 S cm mol− . The Ostwald dilution constnat of the electrolyte is : (1) 2.5 (2) 1 2.5 10−  (3) 3 2.5 10−  (4) 4 2.5 10−  (27.) The best conductor of electricity is a 0.1M solution of: (1) Boric acid (2) Sulphuric acid (3) Acetic acid (4) Propionic acid (28.) The molar conductivity of an electrolyte increases as: (1) dilution increases (2) dilution decreases (3) temperature decreases (4) none of the above is correct (29.) An increase in equivalent conductance of a strong electrolyte with dilution is mainly due to : (1) increase in number of ions (2) increase in ionic mobility of ions (3) 100% ionisation of electrolyte at normal dilution (4) Both 1 and 2 (30.) At 18 C , the conductance of H + and CH COO 3 − at infinite dilution are 315 and 2 1 cm 35mho eq− respectively. The equivalent conductivity of CH COOH 3 at infinite dilution is mho 2 1 cm eq− : (1) 350 (2) 35 (3) 3.5 (4) 315 (31.) Which of the following equation represents variation of molar conductance (ΛM ) with concentration(C) for strong electrolyte : (1) C Λ A C Λ M M  = − + (2) Λ Λ C M M A C  = − (3) Λ Λ C M M A C  = + (4) Λ ΛC M M A C  − = − + (32.) Choose the correct statement(s) from the following: (1) Cathode and anode are negative terminal in electrolytic and galvanic cell (2) Cathode is negative terminal in both electrolytic & galvanic cell (3) Anode is positive terminal in both electrolytic and galvanic cell (4) All of these (33.) Four colorless salt solution are placed in separate test tubes and a strip of copper is placed in each which solution finally turns blue : (1) AgNO3 (2) ( 3 )2 Zn NO (3) ( 3 )2 Pb NO (4) ( 3 )2 Cd NO