Ten state attorneys general on Wednesday accused Google of illegally abusing its monopoly over the technology that delivers ads online, adding to the company’s legal troubles with a case that strikes at the heart of its business. The state prosecutors said that Google overcharged publishers for the ads it showed across the web and edged out rivals who tried to challenge the company’s dominance. They also said that Google had reached an agreement with Facebook to limit the social network’s own efforts to compete with Google for ad dollars. Google said the suit was “baseless” and that it would fight the case