First-order half-life
Which statement is true of a first-order reaction?
Answer D: explanation for every choice
A
A half-life proportional to starting concentration describes a zero-order reaction.
B
A rate independent of concentration also describes zero order.
C
A linear 1/[A] plot indicates second order. First order gives a linear ln[A] plot.
D
Correct. t½ = 0.693/k depends only on the rate constant.
TakeawayFirst order: constant half-life, linear ln[A] versus t.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp106.