Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET202522 Apr 2025Evening ShiftChemistryChemical KineticsActual

The half life values for two different first order reaction A and B are 75 minute and 2.5 hour respectively. What is the r_B r_A ratio of rate constants?

Options

  1. A2 0
  2. B4 5
  3. C14 2
  4. D22 0

Correct answer

A. 2 0

Step-by-step solution

The half-life t_ 1/2 and rate constant k for a first-order reaction are related by t_ 1/2 = 0.693 k . Reaction A has t_ 1/2,A = 75 minutes while reaction B has t_ 1/2,B = 2.5 hours, which is equivalent to 2.5 60 = 150 minutes. The rate constants are therefore k_A = 0.693 75 and k_B = 0.693 150 . The ratio k_A k_B = 150 75 = 2.0 matches option A .

Practice Chemical Kinetics on Quantrex Academy →

More from Chemical Kinetics

When the concentration of the reactant in a given reaction is halved and if the rate of reaction is halved, the order of the reaction is: 2026A first order reaction is 50%complete in 30 minutes at 300 K and in 10 minutes at 320 K. The activation energy of the reaction (E_a ) is: [R=8.314 J K ⁻¹ mol ⁻¹ ; log 2 = 0.3010; l 2026In the synthesis of NH₃ from H₂ and N₂ , if 6 10⁻² mole of hydrogen disappears in 10 minutes, the number of moles of NH₃ formed in 0.3 minutes is: 2026The initial pressure of the system before decomposition for a first order gas phase reaction A_ (g) B_ (g) + C_ (g) was P_i . After lapse of time 't', total pressure of the system 2026Which of the following factors is altered by the addition of a catalyst during a chemical reaction? 2026The rate constants for two different reactions, k₁ and k₂ are 10¹⁶ e^ -2000/T and 10¹⁵ e^ -1000/T respectively. The temperature at which k₁ = k₂ is 202660% of a first order reaction was completed in 60 min, then 50% of the same reaction can be completed in: [log 4 = 0.60, log 5=0.69] 2026Identify the correct values to be plotted in the graph, the slope of which can be used to determine the activation energy of a reaction. 2026 Full Chemical Kinetics list All MHT CET PYQs