JEE Main · 2019 · Shift-IeasyCK-073

Decomposition of X exhibits a rate constant of 0.05\,g/year. How many years are required for the decomposition of 5\,g…

Chemical Kinetics · Class 12 · JEE Main Previous Year Question

Question

Decomposition of X exhibits a rate constant of 0.05μg/year0.05\,\mu\mathrm{g/year}. How many years are required for the decomposition of 5μg5\,\mu\mathrm{g} of X into 2.5μg2.5\,\mu\mathrm{g}?

Options
  1. a

    20

  2. b

    40

  3. c

    25

  4. d

    50

Correct Answerd

50

Detailed Solution

Rate constant units: μg/year\mu\mathrm{g/year} — this is a zero order reaction.

For zero order: [X]=[X]0kt[\mathrm{X}] = [\mathrm{X}]_0 - kt

2.5=50.05×t2.5 = 5 - 0.05 \times t 0.05t=2.50.05t = 2.5 t=50yearst = 50\,\mathrm{years}

Answer: Option (4) — 50 years

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