The functional group can always be found in a carbohydrate molecule. see section 5.1 ( page 109) .

The word filling the space is "hydroxyl".
The complete sentence will be as below:
The hydroxyl functional group can always be found in a carbohydrate molecule. The chemical formula of hydroxyl group OH. As the formula shows it is a bounding of Oxygen (O) and Hydrogen (H) = (OH) 

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.

it's c. elements are placed in rows based on how may valencies electrons have.