Unit 1: Taxing goods with negative externalities: Fizzy drinks

Thanks to tutor2u for pointing out this Telegraph article

http://www.telegraph.co.uk/foodanddrink/foodanddrinknews/7400304/New-York-Citys-mayor-plans-soda-tax.html

a) What are the negative externalities associated with fizzy drinks?
b) Is there any other sort of market failure present here?
c) Using a S&D diagram, discuss how successful the proposed tax would be in reducing the market failure