Chemistry carries the highest scoring potential in JEE for anyone who keeps the three branches separate in revision. This set covers physical chemistry numericals, organic reaction mechanisms and named reactions, and inorganic chemistry including periodic trends, chemical bonding and coordination compounds. Organic questions show the mechanism arrow by arrow, so the reasoning transfers to reactions you have not seen before.
The molar conductivity of a weak electrolyte increases with dilution because:
Answer: B
At higher dilutions, weak electrolytes ionize more completely, increasing degree of ionization and thus molar conductivity
Q.91Easy
Which of the following best explains why diamond is harder than graphite?
Answer: B
Diamond has a 3D tetrahedral covalent network structure with C-C bonds in all directions, while graphite has layered structure with weak van der Waals forces between layers
Q.92Medium
For the reaction 2A(g) ⇌ B(g) + C(g), if initial pressure is 2 atm and degree of dissociation is 0.5, what is the total pressure at equilibrium?
Answer: A
Initial: 2 atm of A. At equilibrium with α = 0.5: A dissociates to (1-0.5)×2 = 1 atm, producing B and C each at 0.5 atm. Total = 1 + 0.5 + 0.5 = 2 atm × (1 + α) = 2 × 1.5 = 3 atm
Q.93Easy
Which of the following factors does NOT affect the value of the equilibrium constant Kc?
Answer: C
Kc depends only on temperature. Pressure, concentration changes, and catalysts do not alter Kc value—they shift equilibrium position but not the constant itself.
Q.94Medium
A solution contains 0.1 M weak acid HA (Ka = 1×10⁻⁵). The degree of ionization is approximately:
Answer: D
For weak acid: α = √(Ka/C) = √(1×10⁻⁵/0.1) = √(1×10⁻⁴) = 0.01 or 1%. Using exact formula: α ≈ 0.0316 (3.16%)
Q.95Hard
At 298 K, ΔG° for a reaction is -20 kJ/mol. The reaction quotient Q = 0.01 when Kp = 1000. Which statement is true?
Answer: A
ΔG° = -20 kJ/mol (negative, spontaneous). Since Q (0.01) < Kp (1000), reaction shifts forward. ΔG = ΔG° + RTlnQ = -20 + 8.314×298×ln(0.01) will be more negative, confirming forward reaction.
Q.96Easy
The molar heat capacity at constant pressure (Cp) for an ideal gas is 29 J/(mol·K). Its molar heat capacity at constant volume (Cv) is approximately:
Answer: A
Cp - Cv = R = 8.314 J/(mol·K). Therefore, Cv = 29 - 8.314 ≈ 20.7 ≈ 20.8 J/(mol·K). This indicates a diatomic gas (Cp = 27 R, Cv = 25 R).
Q.97Easy
In a first-order reaction, if the half-life is 10 minutes, the time taken for the concentration to reduce to 41th of initial value is:
Answer: B
For first-order reaction, each half-life reduces concentration by 50%. After 1st half-life (10 min): 50% remains. After 2nd half-life (20 min): 25% remains = 41th. Total time = 2 × 10 = 20 minutes.
Q.98Easy
Which of the following compounds exhibits optical isomerism?
Answer: B
2-bromobutane has a chiral center (C2 with four different groups: Br, H, CH3, and C2H5), exhibiting optical isomerism. Other options lack a true chiral center.
Q.99Easy
The IUPAC name of (CH3)3C-CH2-OH is:
Answer: B
The structure has 5 carbons with main chain having OH at position 1 and two methyl groups at position 2. IUPAC name is 2,2-dimethyl-1-propanol.
Q.100Easy
Which reagent is used to distinguish between primary and secondary alcohols?
Answer: B
Lucas reagent (HCl + ZnCl2) forms turbidity with primary alcohols immediately, secondary alcohols after 5 minutes, and tertiary alcohols instantly with dehydration.