Question

The half-life of strontium-91, 91

38Sr is 9.70 h. Find

(a) its decay constant, and (5pts)

(b) for an initial 1.00-g sample, the activity after 15 hours.

Answer 1

Half life of $^{91}_{38} Sr= T_{\frac{1}{2}}= 9.7$

= 9.7×60×60

=34920s

$T_{\frac{1}{2}}\lambda$ = 0.693

$\lambda$ = 0.693/T$_\frac{1}{2}$

= 0.693/34920

decay constant= 1.9845×10^-5