PYQ Vault
EbooksTutor

Two first-order reactants with different half-lives: when do their concentrations reach a given ratio

The same question, asked 2 times: 26 Jun 2022*, 3 Apr 2025. Every wording below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    26 Jun 2022

    54
    A flask is filled with equal moles of AA and B. The half lives of AA and BB are 100 s100\text{ }s and 50 s50\text{ }s respectively and are independent of the initial concentration. The time required for the concentration of AA to be four times that of BB is s. (Given: ln⁡2=0.693\ln2 = 0.693 )

  2. Question 2

    3 Apr 2025

    30
    In a reaction A+B→CA + B \rightarrow C, initial concentrations of AA and BB are related as [A]0=8[B]0\lbrack A\rbrack_{0}= 8\lbrack B\rbrack_{0}. The half lives of AA and BB are 10 min and 40 min . respectively. If they start to disappear at the same time, both following first order kinetics, after how much time will the concentration of both the reactants be same?

    Tap an option to check your answer.