Afirst-order reaction has a half-life of 20.0 minutes. starting with 1.00 × 1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Half-life time of a reaction is time at which reactant concentration becomes half of its initial value.

Half-life of the first order reaction is 20 min. Rate constant can be calculated as follows:

The rate expression for first order reaction is as follows:

initial number of molecules of reactant are , time is 100 min thus, putting the values to calculate number of reactant at time 100 min,

On rearranging,

Or,

Therefore, number of molecules unreacted will be

- "the acute form of diverticulitis can manifest itself with one or more severe attacks of infection and inflammation.

the inflammation of diverticulitis can eventually result in a bowel obstruction, which may cause constipation, thin stools, diarrhea, abdominal swelling or bloating, and abdominal pain."

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.