Question

question 7
which of the following is a drawback of biofuels such as ethanol?
the energy to make ethanol is about equal to the energy it puts out.
it is much more expensive than gasoline.
there are few places to grow the plants used to make ethanol.
when burned, ethanol produces more emissions than coal.

Explanation:

Ethanol production often requires significant energy input, and in some cases, the energy used to produce ethanol can be close to the energy it releases. This means its net - energy gain is low, which is a drawback. Ethanol isn't always much more expensive than gasoline. There are many places to grow ethanol - producing plants like corn or sugarcane. Ethanol burns cleaner than coal and produces fewer emissions.

Answer:

The energy to make ethanol is about equal to the energy it puts out.