Atmospheric pressure decreases as altitude increases. In other words, there is more air pushing down on you at sea level, and there is less air pressure pushing down on you when you are on a mountain. If hexane (C6H14), octane (C8H18), and octanol (C8H17OH) are heated evenly at different altitudes, rank them according to the order in which you would expect them to begin boiling.

Explanation:

Boiling point is the temperature at which vapor pressure of a liquid becomes equal to the atmospheric pressure.

So, more is the number of carbon atoms present in a compound that are linearly attached to each other more will be its boiling point. This is because then there are more intermolecular forces present in it and also it occupies more surface area.

Hence, in order to break these intermolecular forces more heat is required. As a result, boiling point of the compound increases.

Therefore, we can conclude that given compounds are ranked according to the increasing order in which you would expect them to begin boiling as follows.

    Hexane at high altitude < Octane at high altitude < Octane at sea level  < Octanol at sea level      

the answer is c. nacl