a. i. Trial Balance
A trial balance is a list of balances extracted from the ledger accounts to test the arithmetic accuracy of the various ledger accounts. It helps check if the additions and subtractions made in the ledger are correct.

Errors not revealed by a trial balance:

1. Error of complete omission
   This occurs when a transaction is completely left out from the books.
2. Error of principle
   This arises when an incorrect accounting principle is applied, such as classifying capital expenditure as revenue.
3. Error of commission
   This happens when a transaction is recorded in the wrong person’s account but the correct side of the account is used.
4. Error of original entry
   This occurs when an incorrect amount is entered at the source.
5. Compensating error
   This is when two or more errors cancel each other out.
6. Complete reversal of entry error
   This happens when the correct amounts are entered on the wrong side of the accounts.

a. ii. Suspense Account
A suspense account is a temporary account used to record transactions whose final destination cannot be determined at the time of recording. Transactions are held in the suspense account pending the discovery and correction of errors through journal entries, after which the account is closed​(Foundation Nov 2020).