I think last one is Ohio?
NEAVDAA (RIP, 2NC) | Guess the encoded US states (chessboard edition - very hard)

Alabama?
Which one?(there may be or there may not be)
Also, you should make a list with all the answers (where you don't know you can use a dash as a placeholder).

1. RI
2. Virginia
3. Alabama
4. Massachusetts
1 and 4 are wrong, 2 is almost correct

1. West Virginia
2. Alabama
3. Hawai’i
4. Mississippi
All are wrong but if you move two of the answers to the next number (or 1 in case of 4) those two answers will be correct

1. Mississippi
2. West Virginia
3. Alabama
4. Hawai’i
2 and 3 are correct but 1 and 4 are still wrong
1. (easy)
hint: P=0, p=1, B=2, ... q=9; 10->ZAB
2. (hard)
hint: ELTcBV0zBrTmBVFzELTcVbFzELTcBV0zBrTmBVFzEJhmBAXzwrUeBABzwVU5BVFDBrU1BZdzurUpBZXzvrTmVb0zSVUfBZvztVUjBZlzBphcBZpzxbU4BZFzwbUbBV0DELUnBZ0zBrTmBVFzELTcVbFzELTcBV0zBrTmBVFzEJ== +7
3. (hard)
hint:
4. (impossible)
hint: error 404 not found