Answer:

Explanation:
From the question we are told that:
Pressure 
Temperature 
Volume 
Heat Produced 
Generally the equation for ideal gas is mathematically given by



Therefore


Since
Heat of combustion of Methane=889 kJ/mol
Heat of combustion of Propane=2220 kJ/mol
Therefore

Comparing Equation 1 and 2 and solving simultaneously




Therefore
Mole fraction 0f Methane is mathematically given as



Answer and Explanation:
The explanation given in the problem is correct but not totally encompassing.
Van der waals interactions are a type of hydrophobic interaction, in which they do not interact with the polar water molecule. Covalent bonds involve the sharing of electrons between atoms of relatively similar electronegativities, and are most often too strong to disrupt by polar molecules of water. Therefore, covalent bonds and van der waals forces have an Intrinsic bond strength value that is independent of the environment.
However, either the partial negative oxygen atom or the partial positive hydrogen atoms in water molecules disrupt hydrogen or ionic bonds. Water is known to form hydrogen bonds with other polar or charged molecules, thus reducing the strength of interaction these molecules would normally have in the absence of water. Basically, these compounds with Hydrogen or Ionic bonds ionize, whether partially or fully in water, thereby leading to a decrease in bond strength in water.
QED!
An atom has an average atomic mass of about 63.5 amu.
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1 amu is equal to 1 gram per mole
so 63.5 amu is just equal to 63.5 grams per mole or 63.5 g/mol
the answer is Cu or copper.
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