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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 131–140 of 143
Topics in JEE Chemistry
Which of the following represents the correct relationship between Qc and Kc for a reaction at non-equilibrium?
A If Qc > Kc, reaction proceeds forward
B If Qc < Kc, reaction proceeds in reverse
C If Qc = Kc, reaction is at equilibrium
D Qc and Kc are always equal
Correct Answer:  C. If Qc = Kc, reaction is at equilibrium
EXPLANATION

Qc = Kc indicates equilibrium. If Qc > Kc, reaction shifts backward; if Qc < Kc, reaction shifts forward.

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Which statement about entropy is correct?
A Entropy always decreases in a spontaneous process
B Entropy of an isolated system always increases or remains constant
C Entropy of a perfect crystal at 0 K is positive
D Entropy decreases with increase in temperature
Correct Answer:  B. Entropy of an isolated system always increases or remains constant
EXPLANATION

According to the second law of thermodynamics, entropy of an isolated system increases or remains constant (ΔSuniverse ≥ 0).

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Which of the following is a colligative property?
A Vapor pressure of solvent
B Boiling point elevation
C Color of solution
D Solubility of solute
Correct Answer:  B. Boiling point elevation
EXPLANATION

Boiling point elevation depends only on the number of solute particles, not their identity, making it a colligative property.

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The Henry's law constant for CO₂ in water at 25°C is 1.67 × 10⁻³ mol/(L·atm). What is the solubility of CO₂ when its partial pressure is 0.8 atm?
A 1.34 × 10⁻³ mol/L
B 2.09 × 10⁻³ mol/L
C 0.134 mol/L
D 1.34 mol/L
Correct Answer:  A. 1.34 × 10⁻³ mol/L
EXPLANATION

Using Henry's Law: S = KH × P = 1.67 × 10⁻³ × 0.8 = 1.34 × 10⁻³ mol/L

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A solution contains 0.1 M HCl and 0.1 M NaOH is added dropwise. At what point does the pH change most rapidly?
A At the start of addition
B At the equivalence point
C After addition is complete
D Midway through the titration
Correct Answer:  B. At the equivalence point
EXPLANATION

The pH changes most steeply at the equivalence point in an acid-base titration because the buffer capacity is minimum at this point.

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At 25°C, the solubility product (Ksp) of AgCl is 1.8 × 10⁻¹⁰. What is the molar solubility of AgCl in pure water?
A 1.34 × 10⁻⁵ M
B 4.24 × 10⁻⁶ M
C 2.68 × 10⁻⁵ M
D 9 × 10⁻¹¹ M
Correct Answer:  A. 1.34 × 10⁻⁵ M
EXPLANATION

For AgCl ⇌ Ag⁺ + Cl⁻, Ksp = [Ag⁺][Cl⁻] = s × s = s². Therefore, s = √(1.8 × 10⁻¹⁰) = 1.34 × 10⁻⁵ M

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The first ionization energy of sodium is lower than that of hydrogen because:
A Sodium has larger atomic radius
B Sodium has better shielding effect
C Sodium nucleus has lower charge
D Both A and B
Correct Answer:  D. Both A and B
EXPLANATION

Both larger atomic radius and greater shielding effect in sodium make the valence electron easier to remove compared to hydrogen's single electron.

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The osmotic pressure of a solution is given by:
A π = nRT/V
B π = MRT
C π = CRT
D π = dRT
Correct Answer:  C. π = CRT
EXPLANATION

Osmotic pressure: π = CRT where C is molar concentration. It's a colligative property dependent on number of solute particles.

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Which of the following is an extensive property?
A Refractive index
B Surface tension
C Entropy
D Density
Correct Answer:  C. Entropy
EXPLANATION

Entropy is an extensive property (depends on amount of substance). Refractive index, surface tension, and density are intensive properties.

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For a spontaneous process at constant T and P, the condition is:
A ΔH < 0
B ΔS > 0
C ΔG < 0
D ΔU < 0
Correct Answer:  C. ΔG < 0
EXPLANATION

At constant temperature and pressure, ΔG < 0 is the criterion for spontaneity, where ΔG = ΔH - TΔS.

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