Cryptocurrency Blockchain Technology Fundamentals 2

Question 1

What is a Merkle tree used for in a blockchain block?

Accepted Answer

To efficiently verify transaction integrity

Answer

A Merkle tree hashes transactions in pairs up to a single root hash, allowing efficient and tamper-evident verification of any transaction in the block.

Question 2

Which field in a block header links it cryptographically to the previous block?

Accepted Answer

Previous block hash

Answer

The previous block hash field contains the hash of the preceding block, creating the cryptographic chain that makes altering past blocks computationally infeasible.

Question 3

What does 'immutability' mean in the context of blockchain?

Accepted Answer

Confirmed records cannot be altered without invalidating the chain

Answer

Immutability means that once data is confirmed and buried under subsequent blocks, changing it requires re-mining all later blocks, making tampering practically impossible.

Question 4

In a public blockchain, who is allowed to participate as a node?

Accepted Answer

Anyone with the required software

Answer

Public blockchains are permissionless, meaning anyone can download the software and join the network as a full or light node without special approval.

Question 5

What is a '51% attack' on a Proof-of-Work blockchain?

Accepted Answer

When a single entity controls the majority of hash rate and can rewrite recent history

Answer

If one miner or pool controls over 50% of the network's hash rate, they can reverse recent transactions and perform double-spends, undermining chain integrity.

Cryptocurrency Practice Test

Cryptocurrency Practice Test

Cryptocurrency Blockchain Technology Fundamentals 2