What is the decay constant of 23892u whose half-life is 4.5*109year?

Answer is: decay constant for uranium-238 is 1,54·10⁻¹⁰ 1/y.

The half-life for the radioactive decay of U-238 is 4.5 billion years and is independent of initial concentration.

t1/2 = 4.5·10⁹ y.

λ = 0,693 : t1/2.

λ = 0,693 : 4.5·10⁹ y.

λ = 1,54·10⁻¹⁰ 1/y.

λ - decay constant.

Decay constant is proportionality between the size of a number of radioactive atoms (in this example uranium) and the rate at which the number of radioactive uranium atoms decreases because of radioactive decay.