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:
True
Explanation:
An orbital is is the space occupied by a pair of electrons. The maximum number of electrons in an orbital is 2.
The maximum number of electrons in in the orbitals are two.
For s-sublevel with one orbital we have two electrons
p-sublevel with three orbitals we have six electrons
d - sublevel with five orbitals we have ten electrons
f - sublevel with seven orbitals we have fourteen electrons
Each orbital can take a maximum of two electrons.
Carbon is stored in the ocean
Answer:
The difference between liquid nitrogen and nitrogen gas is liquid nitrogen gas is man made or caused by humans but, nitrogen gas takes place naturally in the earths atmosphere.
Explanation:
Hope this helps :)