\(N_{Pb}=N_{0.}\) (\(1-2^{-\frac{t}{T}}\) )=\(\Delta\) N

Mà m=\(\frac{N}{N_{A}}.A\) \(\rArr\frac{m_{Pb}}{m_{U}}=\frac{206.N_{Pb}_{}}{238N_{U}}=\frac{23,15}{46,97}\)

\(\rArr\frac{\Delta N}{N}=\frac{N_{Pb}}{N_{U}}=\frac{23,15.238}{46,97.206}\)

\(\rArr\frac{N_{o}.(1-2^{-\frac{t}{T}})}{N_{o}.2^{-\frac{t}{T}}}=\frac{23,15.238}{46,97.206}\left(\ast\right)\)

Có T=\(4,47.10^9\) thay vào (*)

\(\rArr t=2,9.10^9\left(năm\right)=2,9\) (tỉ năm)

Ta có:

T=15(h); Ho=\(2.10^{-6}\left(Ci\right)=2.10^{-6}.3,7.10^{10}=74000\left(Bq\right)\)

\(H=\frac{502}{60}=\) ~8,37 (Bq)

\(\rArr H=Ho.2^{-\frac{t}{T}}\rarr\frac{H}{Ho}=2^{-\frac{7,5}{15}}\rArr\frac{8,37.V}{74000}=2^{-\frac{7,5}{15}}\rArr V\) =~6254 (cm^3)= 6,25 (l)

a, R = 1,4.10^-15 . 226^1/3 = 8,53.10^-15

b, E=[88.1,007276 + (226-88).1,008665 - 226,0254].931,5= ~1686,6 (J)