The final balance of the purchase book is debited to the Purchases Account. Let's understand why:

Meaning of Purchase Book:
The purchase book is a book of original entry which records all credit purchases made by a business. It is used to record all credit purchases of goods on credit made by the business.

Recording in Purchase Book:
When a business purchases goods on credit, it records the transaction in the Purchase book. The entry is recorded by debiting the Purchases account and crediting the supplier's account.

Final Balance in Purchase Book:
At the end of the accounting period, the total of the purchase book is calculated. This total represents the total amount of credit purchases made during the period. This total is then transferred to the Purchases account in the ledger.

Debiting the Purchases Account:
Since the Purchases account is a nominal account, it is debited with the total amount of credit purchases made during the period. This is done to increase the balance of the account.

Reasons for Debiting Purchases Account:
The reasons for debiting the Purchases account are:

- The Purchases account represents the cost of goods purchased by the business on credit.
- The Purchases account is a nominal account and nominal accounts are always debited when they have an increase in balance.

Conclusion:
Thus, it can be concluded that the final balance of the purchase book is debited to the Purchases account as it represents the cost of goods purchased by the business on credit.