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.
In enzyme catalysis, the Michaelis constant (Km) represents:
Answer: B
Km is a characteristic constant for an enzyme-substrate pair, representing substrate concentration when v = Vmax/2
Q.426Easy
For a reaction with rate law Rate = k[A]⁰[B]¹, if [B] is increased 4 times while [A] remains constant, the rate increases by:
Answer: B
Since the reaction is first-order in B and zero-order in A, Rate ∝ [B]. Increasing [B] by 4 times increases Rate by 4 times
Q.427Hard
In the reaction mechanism: (1) A + B ⇌ AB (fast), (2) AB + C → ABC (slow), the order predicted from this mechanism is:
Answer: C
Rate = k₂[AB][C]. From fast equilibrium: [AB] = K₁[A][B]. So Rate = k₂K₁[A][B][C], making it third-order overall
Q.428Medium
The temperature coefficient (Q₁₀) for a reaction is 2.5. If the rate at 300 K is r, then the rate at 320 K is approximately:
Answer: B
Q₁₀ = rate at (T+10)/rate at T. For 300K to 320K (two 10K intervals), rate = r × 2.5² = 6.25r
Q.429Easy
For the reaction A → B, experimental data shows: [A] vs time is a straight line. This indicates:
Answer: B
A straight line in [A] vs time plot indicates [A] = [A]₀ - kt, which is the integrated rate law for zero-order reactions
Q.430Hard
In the complex reaction: A + B → I (fast equilibrium), I + B → C (slow), the rate law derived from this mechanism is:
Answer: B
Rate = k₂[I][B]. From equilibrium: [I] = K₁[A][B]. Therefore: Rate = k₂K₁[A][B]², which is second-order in B
Q.431Medium
The pre-exponential factor (A) in the Arrhenius equation is related to:
Answer: C
The pre-exponential factor accounts for collision frequency, proper orientation (steric factor), and the Maxwell-Boltzmann energy distribution of molecules
Q.432Easy
For an elementary reaction: A + A + B → Products, the rate law is:
Answer: B
For elementary reactions, the rate law is determined by the stoichiometry: Rate = k[A]²[B], as 2 A molecules and 1 B molecule participate
Q.433Easy
For the reaction 2NO + O₂ → 2NO₂, the rate law is Rate = k[NO]²[O₂]. What is the overall order of reaction?
Answer: C
Overall order = sum of exponents in rate law = 2 + 1 = 3 (third order)
Q.434Easy
Half-life of a first-order reaction is 30 minutes. What fraction of reactant remains after 90 minutes?
Answer: C
After 90 min = 3 half-lives, remaining = (21)³ = 81
Q.435Medium
The rate constant of a reaction increases from 4 × 10⁻³ s⁻¹ to 8 × 10⁻³ s⁻¹ when temperature increases from 300K to 310K. Calculate activation energy (R = 8.314 J/mol·K)
