In the Daniel cell constructed in the laboratory, the voltage observed was 0.9 V instead of 1.1 V of the standard cell. A possible explanation is

1) Zn electrode has twice the surface of Cu electrode 2) mole ratio of Zn²⁺ : Cu²⁺ is 2 : 1

(3) [Zn²⁺ > Cu²⁺] 4) Zn²⁺ < Cu²⁺

152. In a galvanic cell increase in the concentration of the solution at the cathode

1) decreases the EMF (2) increases the EMF3) does not change the EMF 4) reverse cell reaction

1) decrease of temperature 2) increase in the dimension of the electrodes

3) increase in the concentration of Cu²⁺ ions (4) increase in the concentration of Ag⁺ ions

154. E⁰ for Fe²⁺ + 2e → Fe is -0.44 volts and E⁰ for Zn²⁺ + 2e → Zn is -0.76 volt. It means that

1) Fe is more electropositive (2) Zn is more electropositive

3) Zn is more electronegative 4) Fe displaces zinc from its salt solution

155. The standard electrode potentials of Zn and Fe are -0.76 V and -0.41 V respectively. If these electrodes are combined to form a cell and if the cell E.M.F. is positive then the cell reaction is

1) Zn²⁺ + Fe ↔ Zn + Fe²⁺ 2) Zn²⁺ + Fe ↔ Zn + Fe

(3) Zn + Fe²⁺ ↔ Zn²⁺ + Fe 4) none of these

156. Copper is above silver in the electrochemical series. So if a copper electrode is combined with a silver electrode to form a cell, then, when the cell operates

(1) copper is oxidized 2) silver is oxidized 3) silver gains electrons 4) silver loses electrons

157. Copper is below iron and above silver in the electrochemical series. S, we can expect that

(1) copper displaces silver from silver nitrate solution

2) copper displaces iron from ferrous sulphate solution

3) silver displaces copper from copper sulphate solution

4) silver displaces iron from ferrous sulphate solution

1) Cu + 2AgNO₃ → Cu (NO₃)₂ + 2Ag 2) Cu + HgCl₂ → CuCl₂ + Hg

3) Zn + CuSO₄ → ZnSO₄ + Cu (4) Cu + FeSO₄ → CuSO₄ + Fe

159.The reduction potentials of Ag / Ag⁺, Hg / Hg²⁺, Cu / Cu²⁺ and Mg / Mg²⁺ are 0.8 V, 0.79 V, 0.34 V and -2.7V respectively. With the increase in voltage the sequence of deposition of the metal on the cathode is

(1) Ag, Hg, Cu, Mg 2) Mg, Cu, Hg, Ag

3) Ag, Hg, Cu and Mg cannot deposited 4) Al, Cu, Mg and Hg cannot be deposited

3) no reaction will occur 4) water will decompose into H₂ and O₂

1) Fe is oxidized to Fe³⁺ and H₂O is reduced to

2) Fe is oxidized to Fe²⁺ and H₂O is reduced to

(3) Fe is oxidized to Fe²⁺ and dissolved oxygen in water is reduced to OH ^–

4) Fe is oxidized to Fe²⁺ and H₂O is reduced to O₂

162. Magnesium can be used to protect iron structures from corrosion since

1) magnesium is less electropositive element 2) magnesium is light element

3) magnesium is cheap (4) magnesium acts as the anode and gets oxidized in preference to iron

163. Iron pipes lying under acidic soil are often attached to blocks of magnesium for protection from resulting. Magnesium offers protection to iron against corrosion because it

1) prevents air from reaching the surface of iron 2) forms of corrosion – resistant alloy with iron

3) is lighter than iron (4) is more readily converted into positive ions

164. Salt bridge is prepared by dissolving KCl, KNO₃ or NH₄NO₃ in agave solution. This is because velocities of

(1) K⁺, Cl ^–, are equal 2) K⁺ > Cl ^– or

3) 4) K⁺ < Cl^–-,

1) > 0 (2) < 0 3) = 0 4) None of these

1) Zn is reduced to Zn²⁺ 2) copper is oxidized to Cu²⁺

(3) Zn is oxidized and Cu²⁺ is reduced 4) Zn is reduced and Cu²⁺ is oxidized

168. A gas X at 1 atm is bubbled through a solution containing a mixture of 1 MY ^– and 1 MZ ^– at 25⁰C. If the reduction potential is Z > Y > X, then

(1) Y will oxidize X and not Z 2) Y will oxidize Z and not X

3) Y will oxidize both X and Z 4) Y will reduce both X and Z

1) M + X → M⁺ + X ^– (2) M⁺ + X ^– → M + X 3) E_cell = 0.77 V 4) E_cell = -0.77 Y

1) temperature of the solution 2) concentration of the solution

(3) area of the metal exposed 4) nature of the metal

172.When a rod of metal A is dipped in an aqueous solution of metal B (concentration of B²⁺ being 1M) at 25⁰C, the standard electrode potentials are A²⁺ / A = -0.76 volts, B²⁺ / B = +0.34 volts.

(1) A will gradually dissolve 2) B will deposit on A

3) No reaction will occur 4) Water will decompose into H₂ and O₂

1) KCl is an electrolyte 2) K⁺ and Cl ^– ions are isoelectronic

(3) K⁺ and Cl ^– ions have same mobility 4) agar forms good jelly with KCl

174.The electrode potential of an anode metal is +1.12 volts and the electrode potential of cathode metal is -0.73 volts. The E.M.F. of the cell is

(1) 1.85 2) -1.85 3) 0.39 4) -0.39

175. E.M.F. of a cell is accurately measured using

1) volt meter (2) potentiometer 3) galvanometer 4) ammeter

1) 1.26 V 2) -1.26 V 3) -0.7 V (4) +0.7 V

1) 0.04 V 2) 0.42 V (3) 1.56 V 4) 1.18 V

1) +3.04 volts 2) -3.04 volts 3) +2.36 volts (4) -2.36 volts

3) Fe⁺² + 2Al → 3Fe + 2Al⁺³ 4) 2Ag⁺ + H₂ → 2Ag + 2H⁺

3) increase in the dimensions of silver electrode 4) increase in the dimension of copper electrode

1) 1.1 (2) 1.07 3) 1.13 4) 11

1) the Zn electrode has twice the surface of Cu electrode 2) mole ratio Zn²⁺ : Cu²⁺ is 2 : 1

(3) Zn²⁺ > Cu²⁺ 4) Zn²⁺ < Cu²⁺

186. M²⁺ + 2e → M. The metal has a negative reduction potential. This means

1) M cannot displace hydrogen from an acid 2) M is an oxidizing agent

(3) M is a reducing agent 4) M²⁺ is a reducing agent

187. The standard reduction potential values of three metallic cations, X, Y, Z are 0.52, -3.03 and -1.18 V, respectively. The order of reducing power of the corresponding metals is

(1) Y > Z > X 2) X > Y > Z 3) Z > Y > X 4) Z > X > Y

188. Aluminium displaces hydrogen from acids, but copper does not. A galvanic cell is prepared by combining Cu / Cu²⁺ and Al / Al³⁺ has an e.m.f. of 2.0 V at 298 k. If the potential of copper electrodes is +0.34 V, that of aluminium electrode is

1) +2.34 V 2) -2.3 V 3) +1.66 V (4) -1.66 V

1) Gold has lower standard reduction potential than iron

(2) Gold has higher standard reduction potential than iron

3) iron rusts 4) gold is denser

1) Zn cannot displace hydrogen from acids 2) Zn is oxidising agent

(3) Zn is a reducing agent 4) Zn²⁺ is a reducing agent

191.The SRP of three elements A, B, C are -2.37 V, -0.76 V &+0.3 V respectively. Then, in solution

1) C displaces hydrogen 3) C is baser than A and B 3) A displaces B but not C (4) A displaces B and C

3) Y will oxidize both X and Z 4) Y will reduce both X and Z

1) ferrous oxide (2) ferrous hydroxide 3) hydrated ferrous oxide 4) ferric oxide

1) nickel 2) zinc 3) tin (4) any of these

1) aluminium is a noble metal (2) oxygen forms a protective oxide layer

3) iron undergoes reaction easily with water 4) iron forms both divalent and trivalent ions

196. Which of the following solutions will have pH close to 1.0?

(1) 100 mL of (M/10) HCl + 100mL of (M/10) NaOH

2) 55 mL of (M/10) HCl + 45 mL of (M/10) NaOH

3) 10 mL of (M/10) HCl + 90 mL of (M/10) NaOH

4) 75 mL of (M/5) HCl + 25 mL of (M/5) NaOH

197. The pH of 0.1M acetic acid is 3. The % of ionisation of acetic acid is (given Ka = 2.0 × 10^{– 5})

(1) 1% 2) 0.1 % 3) 10% 4) less than 1%

1) 0.005 2) 2 3) 1 (4) 12

a) velocity of K⁺ is greater than that of b) velocity of is greater than that of K⁺

(c) velocities of both K⁺ and are nearly the same d) KNO₃ is highly soluble in water

200. For a sparingly soluble salt A_pB_q, the relationship of its solubility product (Ks) with its solubility (S) is

(a) K_s = S^p+q. P^p. Q^q b) K_s = S^p+q. P^p. Q^p c) K_s = S^pq. P^p. Q^q d) K_s = S^pq. (PQ) ^p+q[IIT 01]

201. If standard electrode potential data are useful for understanding the suitability of an oxidant in a redox titration. Some half cell reactions and their standard potentials are given below:

(aq) + 8H⁺ (aq) + 5e^- → Mn²⁺(aq) + 4H₂O(l) ; E⁰ = 1.51V

(aq) + 14H⁺ (aq) + 6e^- → 2Cr³⁺ (aq) + 7H₂O(l) ; E⁰ = 1.38 V

Fe³⁺ (aq) + e^- → Fe²⁺ (aq) ; E⁰ = 0.77V

Cl₂ (g) + 2e^- → 2Cl^- (aq) ; E⁰ = 1.41V

Identify incorrect statement regarding quantitative estimation of aqueous Fe(NO₃)₂. [IIT 2002]

(a) can be used in aqueous HCl b) can be used in aqueous HCl

c) can be used in aqueous H₂SO₄ d) can be used in aqueous H₂SO₄.

a) cathode to anode in solution b) cathode to anode through external supply

(c) cathode to anode through internal supply d) anode to cathode through internal supply

203. Zn | Zn²⁺ (a = 0.1M) || Fe²⁺ (a = 0.01M) | Fe. The emf of the above cell is 0.2905V. Equilibrium constant for the cell reaction is [IIT 2004]

a) 10^{0.32 / 0.0591} (b) 10^{0.32 / 0.0295} c) 10^{0.26 / 0.0295} d) 10^{0.32 / 0.295}

a) One ampere per second b) 96,500 coulombs per second

c) One ampere for one hour (d) Charge on one mole of electrons

206. ½ H₂(g) + AgCl(s) → H⁺ (aq) + Cl^- (aq) + Ag(s) occurs in the galvanic cell [IIT 85]

a) Ag | AgCl(s) | KCl (sol) | AgNO₃ (sol) | Ag b) Pt | H₂ (g) | HCl (sol) | AgNO₃ (sol) | Ag

c) Pt | H₂(g) | HCl (sol) | AgNO₃ (s) | Ag (d) Pt | H₂ (g) | KCl (sol) | AgCl (s) | Ag

207. Of the following metals that cannot be obtained by electrolysis of the aqueous solution of their salts are

a) Ag and Mg b) Hg and Al (c) Mg and Al d) Cu and Cr [I.I.T. 90]

a) Zn(s) b) Cr(s) c) H₂(g) (d) Fe²⁺ (aq)

c) Y will oxidize both X and Z d) Y will reduce both X and Z

a) M + X → M⁺ + X^- is the spontaneous reaction (b) M⁺ + X^- → M + X is the spontaneous reaction

c) E_cell = 0.77V d) E_cell = -0.77V

213. The compound whose 0.1M solution is basic is [IIT 86]

a) Ammonium acetate b) Ammonium chloride c) Ammonium sulphate (d) Sodium acetate

a) 0.05 V (b) 0.01 V c) 0.00 V d) 0.11 V

a) E_cathode + E_anode b) E_anode - E_cathode (c) E_cathode - E_anode d) E_left + E_right

a) Oxidation (b) Reduction c) Neutralisation d) Redox

c) E_M = E⁰ + n/0.0591 log [Mⁿ⁺] d) None of the above

a) Copper will precipitate b) Iron will precipitate out

c) Copper will be dissolved (d) No reaction will take place

199. The position of some metals in the electrochemical seriesMg < Al < Zn < Cu < Ag. What will happen if a copper spoon is used to stir solution of silver nitrate?

a) The spoon will get coated with Al. b) The alloy of Cu and Al is formed

(c) The solution becomes blue d) There is no reaction

220. In electroplating, the article to be electroplated serves as

(a) Cathode b) Electrolyte c) Anode d) Conductor