Answer:
7.5 mg/L
Explanation:
As the drug elimination is following the first order of reaction mechanism so for such reactions the following equation relates the final and initial amount
[tex]\text {Final amount} = \text {initial amount}(\frac{1}{2} )^{\frac{t}{\text {half life}} }[/tex]
The values given in the question are
Initial concentration = 120 mg/L
Half life = 3 hours.
Time = 12 hours
Thus, putting the given values in the above equation, we get
[tex]\text {Final amount}= 120(\frac{1}{2} )^{\frac{12}{3} }[/tex][tex]= 120(\frac{1}{2} )^{4 } = \frac{120}{16} = 7.5[/tex]
Thus, after 12 hours the concentration of the remaining drug will be 7.5 mg/L.
