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Correct option is (c) Galvanization

The best explanation: Rusting of iron is one of the most common forms of corrosion. To prevent iron from rusting, generally, more ACTIVE metals are coated on it. The metal which is often USED for coating iron is zinc (which is more active) and this process is CALLED galvanization.

The correct option is (b) 1

To EXPLAIN I WOULD SAY: Given,

CONDUCTANCE = conductivity

We know that, conductivity = conductance x cell constant

Since the value of conductivity is equal to conductance, the value of the cell constant is equal to 1.

Right choice is (c) Distance of SEPARATION between the electrodes

Easiest EXPLANATION: Ionic MOBILITY is an inherent PROPERTY of the electrolytic solution and is hence, independent of the distance of separation between the two electrodes. As the charge to size ratio increases, the ionic mobility decreases.

Correct choice is (b) False

To elaborate: A GALVANIC cell is a type of electrochemical cell that converts chemical energy into ELECTRICAL energy. The electrochemical cell which converts electrical energy into chemical energy is CALLED ELECTROLYTIC cell.

Right option is (d) SIZE of the ELECTRODE

To EXPLAIN I would say: Electrode potential is the tendency of an electrode to ACCEPT or to lose electrons. Electrode potential depends on the nature of the electrode, temperature of the solution and the concentration of metal ions in the solution. It doesn’t DEPEND on the size of the electrode.

Correct choice is (c) Strains in METALS affect the rate of corrosion

To explain I WOULD say: More active metals are readily corroded. Presence of impurities in metals enhances the CHANCES of corrosion. PURE metals do not corrode. Corrosion takes place rapidly at bends, scratches, nicks and cuts in the metal. Electrolytes, if present, also increase the rate of corrosion.

Right option is (c) Fuel cells have 100% EFFICIENCY practically

To explain: THEORETICALLY, the fuel cells are expected to have an efficiency of 100%. However, practically they give efficiency of 60-70%. Still, they are much superior to the thermal power plants in which FUELS are burnt to PRODUCE heat which then changes WATER into steam to run the turbine. Such a power plant does not have an efficiency of more than 40%.

The correct option is (d) Photographic cameras with a flash

Explanation: Sodium hydroxide cells have nearly CONSTANT voltage at low DISCHARGE CURRENTS whereas potassium hydroxide cells provide a constant voltage at high discharge currents. Therefore, sodium hydroxide cells are ideal for calculators, HEARING aids and electronic WATCHES whereas potassium hydroxide cells are ideal for photographic cameras with a flash.

Right choice is (d) It should supply Alternating CURRENT(AC)

For explanation I would say: A useful battery is expected to be light and compact to be easily transported. It is expected to have a reasonable LIFESPAN to JUSTIFY its usage. Its voltage should not VARY APPRECIABLY during usage so that it doesn’t adversely affect the circuit it is used in. A battery supplies Direct Current(DC) and not Alternating Current(AC).

Right choice is (b) False

The explanation is: ELECTROPLATING is a process that USES direct electric current to carry metal ions from anode and carry them through the electrolyte containing the metal ion to the CATHODE to get a COHERENT metal COATING.

Correct ANSWER is (b) Sodium metal

Explanation: In the electrolysis of NaCl, if the electrolyte is molten NaCl, then the only ions formed after DISSOCIATION are Na^+ and Cl^– ions. The CATHODE being a negatively charged electrode attracts the POSITIVE Na^+ ions and neutralizes it to form Sodium metal.

The correct option is (b) VACUUM

For explanation I would say: Air and MOISTURE accelerate CORROSION. The most IMPORTANT FACTOR in atmospheric corrosion, overriding pollution or lack of it, is moisture. Presence of gases like SO2 and CO2 in air catalyse the process of corrosion. Iron, when placed in vacuum, does not rust.

Correct CHOICE is (c) STEAM reforming and ELECTROLYSIS

Easiest explanation: Since hydrogen does not exist as a gas on Earth, it must be separated from other ELEMENTS. Hydrogen atoms can be separated from water, NATURAL gas molecules or biomass. The two most common ways to produce hydrogen are steam reforming (using high-temperature steam to produce hydrogen from natural gas) and electrolysis (splitting water).

The correct answer is (a) [CO(NH3)3Cl3]

Explanation: Electrolytes that ionise in SOLUTION have a higher VALUE of conductance. Among the given options, [Co(NH3)3Cl3] does not ionise, whereas the other complexes ionise. THEREFORE, [Co(NH3)3Cl3] will have MINIMUM conductance in solution.

The correct choice is (b) It depends on the potential difference between the two ELECTRODES

Easy explanation: Ionic speed is the speed with which the ion moves in the ELECTROLYTE during CURRENT passage. It depends on the NATURE of the IONS, potential difference, separation between the electrodes and the concentration of the electrolyte. The ionic speed is directly proportional to the potential difference between the electrodes.

The CORRECT choice is (a) 8.314 J mol^-1K^-1

The best I can explain: The universal gas CONSTANT is DENOTED by R and is expressed in units of ENERGY per temperature per mole. Since volts is the SI-Unit of potential, R must also be taken in SI-Units which is J mol^-1K^-1.

Right choice is (a) -0.9 VOLTS

The EXPLANATION is: Given,

STANDARD REDUCTION potential of the reduction half reaction = -0.38 volts

Standard reduction potential of the oxidation half reaction = 0.52 volts

Standard EMF of the cell = [Standard reduction potential of the reduction half reaction] – [Standard reduction potential of the oxidation half reaction]

= -0.38 – (0.52)

= -0.9 volts.

The correct CHOICE is (a) Carl Gassner

The best I can EXPLAIN: In the year 1886, Carl Gassner obtained a German patent on a variant of the wet Leclanché cell, which can be known as the dry cell because it did not have a LIQUID electrolyte. Instead, a mixture of ammonium CHLORIDE and plaster of paris was used.

Right option is (a) Electrolyte is 100% dissociated

To ELABORATE: At infinite dilution, even weak electrolytes behaves LIKE strong electrolytes and undergo complete ionization. HENCE, the electrolyte is 100% dissociated. ALSO, at infinite dilution, the ions are FAR apart and interionic effects disappear.

Correct choice is (c) 0.01M CH3COOH

For EXPLANATION I would SAY: The conductivity of a SOLUTION depends on the strength of the ions that make up the solution because strong electrolytes dissociate easily and increase the number of ions, INCREASING the conductivity of the solution. Since CH3COOH is not a strong electrolyte, and because all of the solutions have the same CONCENTRATION, it has the least value of conductivity.

Correct OPTION is (d) 0.34 volts

Explanation: Given,

STANDARD EMF of the cell = E°cell = 2.71 volts

Standard REDUCTION potential of the ANODE = E°anode = -2.37 volts

E°cell = E°cathode – E°anode

E°cathode = E°cell + E°anode

= 2.71 + (-2.37)

= 0.34 volts.

The correct answer is (d) GRAPHITE

Easy EXPLANATION: Electrodes which do not take part in the chemical reaction during ELECTROLYSIS are KNOWN as INERT electrodes. Gold, silver and graphite do not take part in the process, but graphite is preferred because gold and silver electrodes are expensive.

Right choice is (b) 1M KCl

To explain I WOULD SAY: We know that for electrolytic solutions, ⋀M = ⋀E × valency factor

Where ⋀M = molar CONDUCTIVITY and ⋀E = equivalent conductivity

For KCl, the valency factor is 1. Therefore, for KCl, the value of molar conductivity is equal to its equivalent conductivity. For other IONS, ⋀M > ⋀E as their valency factors are > 1.

Correct answer is (c) 2Fe(s) + O2(g) + 4H^+(aq) → 2Fe^2+(aq) + 2H2O(l)

EASY explanation: 2Fe(s) → 2Fe^2+ + 4e^– is the reaction that OCCURS at the anode.

O2 (g)+4H^+(aq)+4e^–⟶2H2O(l) is the reaction that occurs at the cathode.

2Fe(s) + O2(g) + 4H^+(aq) → 2Fe^2+(aq) + 2H2O(l) is the OVERALL reaction of RUSTING.

The CORRECT option is (c) OXYGEN

The best I can explain: A fuel CELL is composed of an anode, cathode, and an electrolyte MEMBRANE. A typical fuel cell works by passing HYDROGEN through the anode of a fuel cell and oxygen through the cathode.

The correct option is (a) True

Best explanation: SECONDARY CELLS are those cells in which the electrode reaction can be reversed by applying an ELECTRICAL energy. Therefore, they can be used to store electrical energy. So, they are ALSO known as STORAGE cells.

Correct answer is (d) It acts as a depolariser

The explanation is: In a dry cell, in the remaining space between the electrolyte and the graphite cathode, a second PASTE consisting of AMMONIUM CHLORIDE and manganese dioxide is applied. The manganese dioxide acts as a depolariser as it helps to prevent the build-up of hydrogen gas bubbles.

Correct option is (a) Its CONDUCTANCE increases with dilution

The best I can explain: Conductance is dependent on the concentration of the electrolytic solution. It is ALSO inversely proportional to the CONDUCTIVITY of the solution. On dilution, the NUMBER of ions per unit volume reduces, decreasing conductivity and increasing the conductance. The EQUIVALENT conductance increases on dilution ionic mobility increases on dilution.

Correct answer is (a) True

The best explanation: YES, the distance between the electrodes is DIRECTLY proportional to the resistance between them. As the distance between the TWO electrodes increases, the resistance offered by the electrolyte increases and therefore REDUCES the VOLTAGE between them.

Correct ANSWER is (B) Friedrich Kohlrausch

To explain I would say: Friedrich Kohlrausch was a GERMAN scientist who conducted research on the conductive properties of electrolytes. He stated that “at INFINITE dilution, each ion of an electrolyte contributes a characteristic ionic conductance TOWARDS equivalent conductance of electrolyte which is independent of the nature of the other ion present in the solution”.

The CORRECT choice is (b) 6

Explanation: Nernst EQUATION = E°(cell) – \(\FRAC{0.059}{n}\) log10(Anode / Cathode)

On comparing both the FORMULAE,\(\frac{0.059}{n}\) = 9.83 × 10^-3

n= 6.

The correct choice is (b) Cathode: Copper, Anode: Iron

For EXPLANATION I would SAY: The given cell is represented as:

Fe (s) | FESO4 (2 M) || CuSO4 (1 M) | Cu (s)

Since the E° of iron < E° of copper, copper rod acts as the cathode and iron rod acts as the anode.

The correct answer is (d) It does not MAINTAIN electrical neutrality of the electrolytic solutions of the half-cells

For explanation I would say: A salt bridge is a junction that connects the anodic and cathodic COMPARTMENTS in a cell or electrolytic SOLUTION. It maintains electrical neutrality within the internal CIRCUIT, preventing the cell from rapidly RUNNING its reaction to equilibrium.

Right option is (b) They have low internal RESISTANCE

Best explanation: Primary cells cannot be used again and again. Since there is no fluid inside, these cells are ALSO KNOWN as dry cells. The internal resistance is high and the chemical reaction is irreversible. Their initial COST is cheap.

Correct CHOICE is (a) True

Explanation: Fuel CELLS are the devices which convert the energy produced during the combustion of FUELS (chemical energy) like hydrogen, methane, methanol etc. directly into electrical energy. Hence, a fuel cell is a type of ELECTROCHEMICAL cell.

Right CHOICE is (b) 1:3 of HNO3 and HCl

Explanation: Aqua regia also known as royal water is a yellow-orange mixture of CONCENTRATED nitric ACID and hydrochloric acid in the ratio 1:3. It is used by an ALCHEMIST to DISSOLVE noble metals like gold and silver.

Right choice is (a) Sugar in water

Explanation: For a solution to conduct electricity, it REQUIRES the solution to have MOVABLE ions. A solution of sugar in water does not conduct electricity as the sugar MOLECULES do not dissociate to form ions. WHEREAS the salts in the other OPTIONS dissociate to form ions and help conduct electricity.

Correct answer is (c) 2

Explanation: 2AG^+(AQ) + 2e^– → 2Ag(s)

From the equation it is evident that 2Ag^+ TAKES 2 electrons from Cu and NEUTRALIZES to form 2Ag.

The correct OPTION is (d) NaCl

The BEST explanation: In a salt bridge, the ELECTROLYTES like KCl, KNO3 or NH4NO3 are preferred because their ions have almost EQUAL transport number, viz., 0.5, i.e., they move with almost the same speed when an electric current flows through them.