Blockchain and Crypto Blockchain Fundamentals & Architecture

Question 1

What is the primary data structure that gives blockchain its name and immutability?

Accepted Answer

A hash-linked chain of blocks referencing the previous block's hash

Answer

A linked list of encrypted records

Answer

A binary tree of transaction records

Answer

A relational database with append-only tables

Question 2

Approximately how often does Bitcoin's network add a new block to the chain?

Accepted Answer

Every 10 minutes

Answer

Every 1 minute

Answer

Every 30 minutes

Answer

Every 60 minutes

Question 3

What is the genesis block in a blockchain?

Accepted Answer

The first block in the blockchain with no predecessor

Answer

The block containing the highest-value transactions

Answer

The most recently mined block in the chain

Answer

A special block created by the network's founder

Question 4

Which consensus mechanism does Bitcoin's network use to validate new blocks?

Accepted Answer

Proof of Work

Answer

Proof of Stake

Answer

Delegated Proof of Stake

Answer

Proof of Authority

Question 5

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

Accepted Answer

Efficiently summarizing all transactions in a block via recursive hashing

Answer

Storing the public keys of all network participants

Answer

Organizing blockchain nodes in a hierarchical peer-to-peer network

Answer

Encrypting block data before broadcast

Question 6

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

Accepted Answer

Once written, data cannot be altered without invalidating all subsequent blocks

Answer

Data can be deleted but never edited

Answer

Only credentialed validators may modify historical records

Answer

All data is stored in an irreversibly encrypted format

Question 7

What is the purpose of a 'nonce' in Bitcoin's Proof of Work mining?

Accepted Answer

A variable number miners increment until they find a hash meeting the difficulty target

Answer

A unique identifier assigned to each transaction by the sender

Answer

A timestamp embedded in each block to prove chronological order

Answer

A digital signature from the network's lead validator