Eight persons A, B, C, D, E, F, G, and H live on different floors of an eight-floor building, numbered 1 to 8 from bottom to top. One person lives on each floor but not necessarily in the given order.

G lives five floors above C. As many floors are there below C’s floor as above B’s floor. Three floors are there between the floors of B and D. F lives two floors away D. E does not live above H. A doesn’t live on prime numbered floor.

If all the persons live in alphabetical order from the topmost floor to the bottom-most floor, then the floors of how many persons remain unchanged?

Let's solve the floor puzzle step-by-step to find the correct floor arrangement of the eight persons (A, B, C, D, E, F, G, and H) living on floors numbered 1 to 8 (from bottom to top).

Step 1: Analyze the clues for C and G
Clue: "G lives five floors above C."
This means $G\; -\; C\; =\; 5$. Since the building has 8 floors, the possible pairs for (C, G) are:
- Case 1: $C\; =\; 1,\; G\; =\; 6$
- Case 2: $C\; =\; 2,\; G\; =\; 7$
- Case 3: $C\; =\; 3,\; G\; =\; 8$

Step 2: Analyze the clue for B
Clue: "As many floors are there below C’s floor as above B’s floor."
Let's test this for each case:
- For Case 1 ($C\; =\; 1$): there are 0 floors below C. Thus, there must be 0 floors above B, which means $B\; =\; 8$. This is a valid configuration: $C\; =\; 1,\; G\; =\; 6,\; B\; =\; 8$.
- For Case 2 ($C\; =\; 2$): there is 1 floor below C. Thus, there must be 1 floor above B, which means $B\; =\; 7$. However, G is already on floor 7, causing a conflict. So, Case 2 is invalid.
- For Case 3 ($C\; =\; 3$): there are 2 floors below C. Thus, there must be 2 floors above B, which means $B\; =\; 6$. This is a valid configuration: $C\; =\; 3,\; G\; =\; 8,\; B\; =\; 6$.

Step 3: Analyze the remaining clues for Case 1 ($C\; =\; 1,\; G\; =\; 6,\; B\; =\; 8$)
- Clue: "Three floors are there between the floors of B and D."
With $B\; =\; 8$, D must be on floor 4 (since floors 7, 6, and 5 are between them).
- Clue: "F lives two floors away D."
With $D\; =\; 4$, F can be on floor 2 or floor 6. Since G is on floor 6, F must be on floor 2 ($F\; =\; 2$).
- Now, the remaining vacant floors are 7, 5, and 3.
- Clue: "A doesn’t live on prime numbered floor."
However, the remaining floors (7, 5, and 3) are all prime numbers. Thus, A would be forced to live on a prime-numbered floor, which violates the clue. Therefore, Case 1 is invalid.

Step 4: Analyze the remaining clues for Case 3 ($C\; =\; 3,\; G\; =\; 8,\; B\; =\; 6$)
- Clue: "Three floors are there between the floors of B and D."
With $B\; =\; 6$, D must be on floor 2 (since floors 5, 4, and 3 are between them).
- Clue: "F lives two floors away D."
With $D\; =\; 2$, F must be on floor 4 ($F\; =\; 4$).
- The occupied floors so far are: G (8), B (6), F (4), C (3), D (2).
- The remaining vacant floors are 7, 5, and 1.
- Clue: "A doesn’t live on prime numbered floor."
Among the vacant floors (7, 5, 1), 7 and 5 are prime numbers, while 1 is not. Thus, A must live on floor 1 ($A\; =\; 1$).
- Clue: "E does not live above H." (i.e., E lives on a lower floor than H).
The remaining floors are 7 and 5. Therefore, E must be on floor 5 and H must be on floor 7 ($E\; =\; 5,\; H\; =\; 7$).

Final Floor Arrangement:
- Floor 8: G
- Floor 7: H
- Floor 6: B
- Floor 5: E
- Floor 4: F
- Floor 3: C
- Floor 2: D
- Floor 1: A

Step 5: Alphabetical comparison from top to bottom
If all persons are arranged in alphabetical order (A, B, C, D, E, F, G, H) from the topmost floor (8) to the bottom-most floor (1):
- Floor 8: G (changes to A)
- Floor 7: H (changes to B)
- Floor 6: B (changes to C)
- Floor 5: E (changes to D)
- Floor 4: F (changes to E)
- Floor 3: C (changes to F)
- Floor 2: D (changes to G)
- Floor 1: A (changes to H)

Comparing the two arrangements, the floors of None of the persons remain unchanged.