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JEE Chemistry

Chemistry questions for JEE Main — Physical, Organic, Inorganic Chemistry.

143 Q 5 Topics Take Test
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Difficulty: All Easy Medium Hard 41–50 of 143
Topics in JEE Chemistry
What does Faraday's first law of electrolysis state?
A The amount of substance deposited is directly proportional to the charge passed
B The conductivity of solution decreases with dilution
C EMF is inversely proportional to current
D Reduction always occurs at the cathode
Correct Answer:  A. The amount of substance deposited is directly proportional to the charge passed
EXPLANATION

Faraday's first law states that the mass of substance deposited/dissolved during electrolysis is directly proportional to the quantity of electricity (charge) passed through the electrolyte.

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In a galvanic cell, which electrode acts as the negative terminal?
A Cathode
B Anode
C Salt bridge
D Both anode and cathode
Correct Answer:  B. Anode
EXPLANATION

In a galvanic cell, the anode is the negative electrode where oxidation occurs. The cathode is positive where reduction occurs.

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What is the SI unit of electrical conductivity?
A S·m⁻¹
B Ω·m
C S·cm
D Ω·cm⁻¹
Correct Answer:  A. S·m⁻¹
EXPLANATION

Electrical conductivity is measured in Siemens per meter (S·m⁻¹). Ω·m is the unit of resistivity, which is the inverse of conductivity.

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Which of the following statements about electrolysis is INCORRECT?
A Electrolysis is a non-spontaneous process
B In electrolysis, oxidation occurs at the cathode
C Electrical energy drives the electrolysis reaction
D The anode in electrolysis is positively charged
Correct Answer:  B. In electrolysis, oxidation occurs at the cathode
EXPLANATION

In electrolysis, oxidation occurs at the ANODE, not the cathode. The cathode is where reduction occurs. At the anode, electrons are removed from species.

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The Nernst equation relates cell potential to concentration. At 25°C, which form is correct?
A E = E° + (0.059/n) log Q
B E = E° - (0.0592/n) log Q
C E = E° + (0.0592/n) log Q
D E = E° - (0.059/n) log(1/Q)
Correct Answer:  C. E = E° + (0.0592/n) log Q
EXPLANATION

The Nernst equation at 25°C is E = E° + (0.0592/n) log Q, where Q is the reaction quotient and n is the number of electrons transferred.

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What is the charge on one mole of electrons?
A 1.6 × 10⁻¹⁹ C
B 6.022 × 10²³ C
C 96485 C
D 1.6 × 10⁻¹⁹ × 6.022 × 10²³ C
Correct Answer:  C. 96485 C
EXPLANATION

One mole of electrons carries a charge equal to Faraday's constant, which is approximately 96485 C/mol or 96500 C/mol.

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In a galvanic cell, which electrode acts as the anode?
A The electrode where reduction occurs
B The electrode where oxidation occurs
C The electrode connected to the positive terminal
D The electrode made of inert material
Correct Answer:  B. The electrode where oxidation occurs
EXPLANATION

In a galvanic cell, oxidation occurs at the anode. The anode is the negative electrode where electrons are released.

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Which of the following is the SI unit of electrical conductivity?
A S·m⁻¹
B Ω·m
C A·V⁻¹
D S·m²
Correct Answer:  A. S·m⁻¹
EXPLANATION

Electrical conductivity is measured in Siemens per meter (S·m⁻¹). Ω·m is the unit of resistivity, which is the reciprocal of conductivity.

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In the extraction of iron from its ore using a blast furnace, the temperature at the bottom of the furnace reaches approximately 1900°C. At this temperature, which compound primarily acts as the reducing agent?
A Carbon dioxide (CO₂)
B Carbon monoxide (CO)
C Solid carbon (Coke)
D Limestone (CaCO₃)
Correct Answer:  B. Carbon monoxide (CO)
EXPLANATION

At high temperatures in the blast furnace, carbon monoxide (CO) is the primary reducing agent that converts iron oxides to metallic iron. Although coke produces CO, the actual reduction occurs through CO: Fe₂O₃ + 3CO → 2Fe + 3CO₂. This is thermodynamically favorable at furnace temperatures.

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In the preparation of oxygen by thermal decomposition of KClO₃, the catalyst used is:
A MnO₂
B Pt
C Fe₂O₃
D CuO
Correct Answer:  A. MnO₂
EXPLANATION

MnO₂ is the standard catalyst for KClO₃ decomposition, significantly lowering the decomposition temperature from ~400°C to ~240°C. It acts as a heterogeneous catalyst.

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