Final answer:
A hash index is not suitable for range search predicates because it does not preserve the order of the indexed values.
Step-by-step explanation:
A hash index is not suitable for range search predicates because a hash index organizes data based on the hash value of a key. Range search predicates, on the other hand, require searching for values within a specific range. Hash indexes do not preserve the order of the indexed values, making it difficult to perform range searches efficiently.