Can you spot the error?

[Badfish2]

where's the error in this page (simple chemistry knowledge required)

the funniest thing about it is that it's in an ad for student discounts!

http://www.gmcanada.com/english/used/optimum/overview/opti_over_500disc.html

 

[TannerBalls]

H02 isnt water

 

[Salomon_Girl]

(O)---- (H)

\

\

(H)

 

[freestyle_kyle]

hahaha nice

 

[hiphopopotamus]

ya that was simple i caught that

 

[Badfish2]

gold stars.... all of you!