This type of pure substance contains more than one type of element chemically bonded A. Compounds
B. Heterogeneous mixture
C. Homogeneous mixture
D. Elements

A. Compounds

Explanation:

Firstly, don't let the word "pure" confuse you; this is pretty much irrelevant to the question.

The key to answering this question lies in "substance" and "more than one type of element chemically bonded."

Something you ought to memorize is that a substance is either an element or compound. Therefore, you can eliminate choices B./C.

Next, use the part of the definition that says "more than one type of element chemically bonded" to conclude that it's a compound. Not only is this the definition of a compound, but the fact that is says more than one type of element should automatically tell you that it is different from just a regular element (Choice D.).

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.