How to define if default browser opens the needed page

Process.Start("http://example.com"); // <-- put your url there.

void OpenBrowser(string url)
{
    try
    {
        Mouse.OverrideCursor = Cursors.AppStarting;
        Process.Start(url);
    }
    catch (Exception)
    { //swallow: exception is sometimes thrown even though
    } // the call completed without error
    finally
    {
        Mouse.OverrideCursor = null;
    }
}