Answer:
A: Helium or Hydrogen
Explanation:
Terrestrial planets are the 4 inner most planets of the solar system which are mercury, venus, earth, Mars, while the giant planets are the 4 outer most which are Jupiter, Saturn, Uranus and Neptune.
Now, these outer most ones are the surface ones and are surrounded primarily by layers of hydrogen and helium gases.
The correct answer C - acceleration
Answer : The molecular formula of the compound is, 
Explanation :
Molecular formula : It is the representation of substance by the symbols and it denotes the number of atoms of each element present in the compound.
Now count the number of carbon, hydrogen, nitrogen and oxygen atoms present in the given compound.
As we see that in the given compound, there are 8 atoms of carbon element, 3 atoms of oxygen element, 1 atom of nitrogen element, 9 atoms of hydrogen element.
Thus, the molecular formula of the compound will be 
<u>Answer:</u> The mole ratio of H : O in ammonium nitrate is 4 : 3.
<u>Explanation:</u>
We are given a compound named ammonium nitrate having formula 
There are 3 elements in this compound which are nitrogen, hydrogen and oxygen.
To calculate the mole ratio, we write the ratio of their subscripts. For this compound, it is:

The mole ratio of H and O for this compound is 4 : 3.