Classify the sample according to its composition. check all that apply. check all that apply. the sample is a compound. the sample is a homogeneous mixture. the sample is a pure element. the sample is a heterogeneous mixture.

Compound sample: In a compound there remains bond between two or more atoms, which is produced by a chemical reaction. As for example: . Thus water is a compound.

Compound homogeneous mixture: In a material which is produced more than one element but both remains in the same phase. There will be uniformity in the mixture. Like gas with gas, liquid with liquid etc. Example: Air which is mixture of oxygen, nitrogen, carbon di oxide where all the compounds are in gaseous form.

Compound Heterogeneous mixture: The mixture where the compound or elements by which the mixture is prepared are in different phase. Like chalk (CaC in water ((liquid), which is a heterogeneous mixture.  

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

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.