Which term refers to the simplest form of matter that cannot be broken down chemically? A. Element
B. compound
C. Mixture
D. solution

I believe the answer is A, an Element.

Explanation:

It's a substance that cannot be broken down into simpler substances. If I'm wrong, let me know!

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.