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!
Explanation:
Molar mass of Cu = 63.5g/mol
Moles of Cu
= 5.8g / (63.5g/mol) = 0.091mol (B)
To find out the pressure in atm. You must divide 385 by 760. So pressure in atmospheres equals 385/760.
Answer: <u><em>True</em></u>
Explanation:
<u><em>Q. 10g of white powder reacts with 10g of clear liquid. The reaction bubbles and changes color producing a black liquid that has a mass of 13g. What can be ...</em></u>
The question is asking us to determine what gives the Amethyst its purplish color. Amethyst colors range from light to dark purple. The most highly regarded are the transparent deep purple colors. Amethyst ( chemical formula: Si O2 ) is the purple variety of the mineral Quartz.The pure Quartz is often colorless. Amethyst gets its purplish color because of the presence of Iron ( Fe ) and other impurities in the gem. Answer: C. Iron.<span /><span />