In the three-dimensional structure of methane, ch4, the hydrogen atoms attached to a carbon atom are aligned at

Corner of tetrahedral structure

Explanation:

In three dimension methane has tetrahedral structure in which central atom is carbon which has four valance electron.

Each valence electron of carbon is shared by hydrogen atom as there are 4 valence electron in so there will be 4 hydrogen atom

And each hydrogen atom is aligned at the corner of tetrahedral structure of

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.