Fuel efficiency in europe is commonly defined as fuel consumption per 100 [km]. an american car has a fuel efficiency of 32 [mi/gal) and a european car has a fuel efficiency of 5.2 [l/100 km). which car is more efficient?

The European car is more efficient (5.2 vs 7.35 L/100km)

Explanation:

To compare the two efficiencies we have to have them in the same units.

We have that 1 mi. is equal to 1.61 km and 1 gal is 3.785 litres.

The american car efficiency can be expressed as:

We calculate the amount of kilometers the car can make with one litre of fuel. To know the efficiency in L/(100 km) we have to rearrange the expression:

We know now that the american car consumes 7.35 L per 100 km, which is higher than the european car.

So, the European car is more efficient (5.2 vs 7.35 L/100km)

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.