This is relatively easy and there are a couple ways to check what has been indexed in your site.

The first way will require access to Google Webmaster Tools (or GWT for short).

Firstly login to your GWT account and select your site. Go to crawl, sitemaps and you will see a graph.

You will notice that it says web pages, 123 submitted, 50 indexed. This is telling me that I have 50 items from my site indexed but nothing specific.

Clicking on the sitemap here will take you to a more detailed explanation as displayed below.

As you can see the entry highlighted in red, i have a number of posts that have been submitted and a number that has been indexed.

Now another way you can tell what has been indexed without using GWT is by using the site operator search.

Firstly open up a clean, fresh browser and go to Google.com

In the search bar enter:

Site:yourdomain.com

This will bring back everything that google has indexed from your site. You can now look at the specific posts that are indexed. Whatever is not on this list is not indexed.