Since this is just a subset of the 50 States, why not set up "bonus answers" with each of the States not on the list? The displayed answer could be a mild rebuke, such as this:
|Alaska, nope. Take a point off your score / Alaska | ee
|Rhode Island? Really? Now you're just wild-guesssing!/Rhode Island | ee
|Sorry, wrong Dakota./North Dakota|ee
The "|" symbol represents cell separation in the data. The first column is blank. The second has the rebuke first then "/" then the actual State name, and the third column has "ee", which sets the answer up as an extra. |
Countries of Europe 
Countries of Africa 
Countries of Asia
