Of course they are biased. Google has brought a wealth of tools to marketing that makes it easier to target the most profitable market for each ad. Racial bias is of course going to be part of that. With Chinese New Year coming up I am sure some companies are placing ads that target the Chinese. Most of us will not see these ads as we do not search for or visits websites that cater to that market.
When using a search engine like Google, it is important to note that an engine as heavily used Google utilizes many techniques to show most relevant results. Some of those results may appear racially biased if the reason for the results are not understood. First you should know that Google uses a unique algorithm to come up with search results. One of the techniques used is to show what is most heavily searched. There is another factor that should be noted, Google is a personality based browser. What you write/search into Google is made note of and affects the future searches you request.
There is not reason to think that Google's ads are in fact biased against any racial group in the United States. Google is a search engine and simply is a reflection of what we as a world search for. If these searches show a racial bias, then perhaps we as a planet should be concerned.
Google ads are advertisements that appear primarily through the popular internet search engine Google. There is no rational basis on which to assert that the ads are racially biased. Everyone is able to access the website either on their personal computers or in a public space such as a library or a free wi-fi area. If the ads appear to cater to one racial group or another, it is because that group is considered the most likely to browse the websites in question. It would not make sense for the ads to be racially biased, as the internet itself makes such acts impossible to hide, and the company would lose money in the long run if it had a reputation for racial bias.