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ExamsNEETChemistry

The rate constant for a first order reaction is 4.606 × 10⁻³ s⁻¹. The time required to reduce 2.0 g of the reactant to 0.2 g is:

  1. 200 s
  2. 500 s
  3. 1000 s
  4. 100 s

Correct answer: 500 s

Solution

For a first-order reaction, the time can be calculated using the formula t = (2.303/k) * log10([R]₀/[R]). Substituting k = 4.606 × 10⁻³ s⁻¹, [R]₀ = 2.0 g, and [R] = 0.2 g, we get t = (2.303 / 4.606 × 10⁻³) * log10(2.0 / 0.2) = 500 s.

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