Answer:
The number of half-lives that have occurred are 4.
Explanation:
Formula used for number of half lives :
[tex]a=\frac{a_o}{2^n}[/tex]
where,
a = amount of reactant left after n-half lives
[tex]a_o[/tex] = Initial amount of the reactant
n = number of half lives
[tex]a_o=x[/tex]
[tex]a = x-\frac{15}{16}x=\frac{1}{16}x=a[/tex]
[tex]\frac{1}{16}x=\frac{x}{2^n}[/tex]
[tex]2^n=16=2^4[/tex]
n = 4
The number of half-lives that have occurred are 4.
