Question

The barium isotope 133Ba has a half-life of 10.5 years. A sample begins with 1.1×1010 133Ba atoms.

A) How many are 133Ba atoms left in the sample after 4 years.

Answer 1

Half-life of the barium isotope 133 Ba = T_1/2 = 10.5 years

Decay constant =

= 6.601 x 10^-2 yr^-1

Initial number of 133 Ba atoms = N₀ = 1.1 x 10¹⁰ atoms

Number of 133 Ba atoms left after 4 years = N

Time period = T = 4 years

N = 8.45 x 10⁹ atoms

A) Number of 133 Ba atoms left after 4 years = 8.45 x 10⁹ atoms