Answer: a. 2
b. 1 hour
c. Am-237
Explanation:
Half life is the time taken by a reactant to reduce to its original concentration. It is designated by the symbol [tex]t_\frac{1}{2}[/tex].
Formula used :
[tex]a=\frac{a_o}{2^n}[/tex]
where,
a = amount of reactant left after n-half lives = 0.002
[tex]a_o[/tex] = Initial amount of the reactant = 0.008 g
n = number of half lives = ?
Putting values in above equation, we get:
[tex]0.002=\frac{0.008}{2^n}[/tex]
[tex]2^n=4\\\2^n=2^2[/tex]
[tex]n=2[/tex]
Thus two half lives have passed.
2. If two half lives have passed in 120 minutes
one half life will be passed in =[tex]\frac{120}{2}\times 1=60 minutes[/tex] or 1 hour
3. As half life is characteristic of a particular isotope.
Given : the half life of isotope Am-237 is 1 hour or 60 minutes. thus the isotope was Am-237.
