A substance undergoing thermal expansion will expand when heated, substances will mostly expand when heated but when their cold it will undergo contraction.
Answer: The mole ratio of oxygen to pentane for the combustion of pentane is 8 : 1.
Explanation: The given reaction is a type of combustion reaction.
Combustion reaction is a reaction in which a hydrocarbon reacts with oxygen gas to produce water and carbon dioxide gas.
For the reaction of pentane with oxygen, the balanced equation would be:
In the reaction, 1 mole of 
reacts with 8 moles of 
gas.
Thus giving us the mole ratio as
Oxygen : Pentane = 8 : 1
Given data:
Hydrogen (H) = 3.730 % by mass
Carbon (C) = 44.44%
Nitrogen (N) = 51.83 %
This means that if the sample weighs 100 g then:
Mass of H = 3.730 g
Mass of C = 44.44 g
Mass of N = 51.83 g
Now, calculate the # moles of each element:
# moles of H = 3.730 g/ 1 g.mole-1 = 3.730 moles
# moles of C = 44.44/12 = 3.703 moles
# moles of N = 51.83/14 = 3.702 moles
Divide by the lowest # moles:
H = 3.730/3.702 = 1
C = 3.703/3.702 = 1
N = 3.702/3.702 = 1
Empirical Formula = HCN
They must have the same density
Friction of the air, and the surface it is on
