Chemical Kinetics · JEE Advanced previous year questions

2024 2 questions

1. Q432024 · 26 May 2024 · Paper 1· Numerical answer

   Consider the following reaction, $$2{\mathrm{H}}_2(\mathrm{g})+2NO(\mathrm{g})\to {\mathrm{N}}_2(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{g})$$ which follows the mechanism given below: $$2NO(\mathrm{g})\underset{k_{-1}}{\stackrel{k_1}{\rightleftharpoons }}{\mathrm{N}}_2{\mathrm{O}}_2(\mathrm{g})\text{(fast equlibrium)}$$ $${\mathrm{N}}_2{\mathrm{O}}_2(\mathrm{g})+{\mathrm{H}}_2(\mathrm{g})\stackrel{k_2}{\to }{\mathrm{N}}_2\mathrm{O}(\mathrm{g})+{\mathrm{H}}_2\mathrm{O}(\mathrm{g})\text{(slow reaction)}$$ $${\mathrm{N}}_2\mathrm{O}(\mathrm{g})+{\mathrm{H}}_2(\mathrm{g})\stackrel{k_3}{\to }{\mathrm{N}}_2(\mathrm{g})+{\mathrm{H}}_2\mathrm{O}(\mathrm{g})\text{(fast reaction)}$$ The order of the reaction is ____.

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   Answer: 3

2. Q452024 · 26 May 2024 · Paper 2· Numerical answer

   A sample initially contains only U-238 isotope of uranium. With time, some of the U-238 radioactively decays into Pb-206 while the rest of it remains undisintegrated. When the age of the sample is $\mathbf{P}\times 10^8$ years, the ratio of mass of Pb-206 to that of U-238 in the sample is found to be 7. The value of $\mathbf{P}$ is ____. [Given: Half-life of U-238 is $4.5\times 10^9$ years; ${\log }_{e}2=0.693$]

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   Answer: Dropped in the final answer key (full marks to everyone)