Chemistry Edexcel

[Summer :]]

Why are biofuels considered not carbon neural?
what are two effects of a large scale production of biofuels?
which is considered more sustainable bioethanol,biodiesel or miscanthus?

i have no idea whats this related to chemistry, it requires no thinking and i hate memorising whatsoever!! 
i've got a mock tomorrow 

[Saladin]

This is a part of green chemistry.

Biofuels, mainly ethanol and other alchohols, are all carbon compunds, and thus release carbon-dioxide into the atmosphere.

Also, the cost to produce them, such as tactors, harvesters, irrigation all take up fuel.

Now large scale production will mainly cause food prices to rise.

For the last question, you have to give me the stats on each of them.

Hope that helps.