Let's say I've a Merkle tree where leaves are the hashes of some data that needs to be authenticated. Can I verify the whole of them by just using the hash of the root of Merkle tree? If yes, how?
If you need to verify all the data, you are going to have to recompute the entire tree, and compare your root with the root you were given. The power of the Merkle tree comes into effect when you only need to verify a subset of the data.