Answer:
The amount of drug left in his body at 7:00 pm is 315.7 mg.
Explanation:
First, we need to find the amount of drug in the body at 90 min by using the exponential decay equation:

Where:
λ: is the decay constant = 
: is the half-life of the drug = 3.5 h
N(t): is the quantity of the drug at time t
N₀: is the initial quantity
After 90 min and before he takes the other 200 mg pill, we have:

Now, at 7:00 pm we have:

Therefore, the amount of drug left in his body at 7:00 pm is 315.7 mg (from an initial amount of 400 mg).
I hope it helps you!
Answer:
helium
Explanation:
helium has the highest ionization energy level
Answer:
2:1<em><u> </u></em><em><u> </u></em><em><u>of </u></em><em><u> </u></em><em><u>Tc </u></em><em><u>in </u></em><em><u>the</u></em><em><u> </u></em><em><u>periodic</u></em><em><u> table</u></em>
Answer:
sulfide ion
Explanation:
however, when non-metalic elements gain electrons to form anions the end of their name is change to "-ide".foe example, a flourin atom gains one electronto become a flouride ion(F`) and sulfur gains two electrons to become a sulfide ion(s^2)