Single replacement because only one letter is being switched out in the reaction
A water molecule, because of its shape, is a polar molecule. That is, it has one side that is positively charged and one side that is negatively charged. The molecule is made up of two hydrogen atoms and one oxygen atom. The bonds between the atoms are called covalent bonds, because the atoms share electrons.
Answer: The sample that contains the greater number of molecules is water.
Explanation: To calculate the number of molecules, it is used the Avogadro's number ( 
particles/molecules). So, considering that the mass to water and carbon dioxide is 1g (it can be any other number), the relationship between moles and molar weight is:
To water: 
= 0.05 moles.
Therefore,
1 mol ---- molecules
0.05 moles ---- x
x = 
molecules of water.
To carbon dioxide: 
= 0.02 moles.
Therefore,
1 mol ---- molecules
0.02 moles ---- y
y = 
molecules of carbon dioxide.
