Blockchain Developer Core Blockchain Data Structures 2

Question 1

In a Merkle tree, what is stored at each leaf node?

Accepted Answer

The hash of an individual transaction

Answer

The block header

Answer

A pointer to the previous block

Answer

The nonce value

Question 2

What property of cryptographic hash functions ensures a tiny input change produces a completely different output?

Accepted Answer

The avalanche effect

Answer

Collision resistance

Answer

Determinism

Answer

Preimage resistance

Question 3

How does a block reference the block before it in the chain?

Accepted Answer

By including the previous block's hash in its header

Answer

By storing the previous block's full data

Answer

By using a sequential database ID

Answer

By timestamp comparison

Question 4

What is the primary benefit of a Merkle tree for lightweight (SPV) clients?

Accepted Answer

They can verify a transaction's inclusion without downloading the full block

Answer

They can mine blocks faster

Answer

They eliminate the need for hashing

Answer

They compress all transactions into one byte

Question 5

If a Merkle tree has an odd number of leaf nodes, how is this commonly handled in Bitcoin?

Accepted Answer

The last hash is duplicated to make a pair

Answer

The tree is rejected

Answer

A zero hash is appended

Answer

The odd node becomes the root directly

Question 6

What data structure is a blockchain fundamentally based on?

Accepted Answer

A hash-linked list of blocks

Answer

A balanced binary search tree

Answer

A hash table

Answer

A doubly-linked circular queue

Question 7

Why is a blockchain considered tamper-evident?

Accepted Answer

Altering one block changes its hash and breaks all subsequent links

Answer

Blocks are encrypted with private keys

Answer

Miners manually inspect every block

Answer

Each block has a digital watermark