A first-order decomposition reaction has a rate constant of 0.00140 yr−1. How long does it take for [reactant] to reach 12.5% of its original value? Be sure to report your answer to the correct number of significant figures.

Explanation:

rate constant k = .00140 yr⁻¹

k is rate constant , t is time taken for  decrease of initial concentration of a to a₁

Here a = 100 , a₁ = 12.5

.00140 = (1 / t )  x  ln 100 / 12.5

.00140 = 2.07944 / t

t = 1485.3 yr .

the population of unionid mussels in the hudson river decreased after zebra mussels were introduced. zebra mussels, a nonnative species, competed with the unionid mussels for food. the zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. the unionid mussel population decreased due to a lack of food.

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