WorksheetsBlockchain quiz
Total questions: 20
Worksheet time: 10mins
What is a key reason blockchain has become popular?
Centralized data control
Ability to modify data easily
Decentralized verification and immutability
Lack of cryptography
What role do Merkle Trees play in blockchain?
They encrypt data
They help verify large amounts of data efficiently
They change hash outputs
They generate private keys
A blockchain hash function is considered secure because it is:
Easily reversible
A one-way, irreversible function
Based on compression
Unrelated to block data
What does a digital signature verify?
Only the message length
Only the sender’s identity
Both authenticity and integrity
Only the receiver’s identity
In a blockchain block, the Nonce is used to:
Store transaction data
Modify the hash until criteria are met
Identify users
Encrypt messages
A block is considered valid when its hash:
Contains no zeros
Starts with a required number of leading zeros
Is encrypted
Matches the previous block’s data
Changing data inside a block will:
Keep the hash similar
Produce a completely different hash
Not affect the hash
Only change the last digits
Mining Bitcoin requires:
Ordinary smartphones
Extremely low power devices
High computational hardware
Manual calculations
In Bitcoin, miners are rewarded for:
Guessing the correct public key
Solving cryptographic puzzles
Updating usernames
Verifying email addresses
The double-spend problem occurs because digital items:
Cannot be copied
Are always unique
Can be duplicated easily
Cannot be verified
Blockchain solves double-spending through:
Centralized servers
Decentralized verification
Manual checks
Hardware locks
How often is a new block added to the Bitcoin blockchain?
Every 10 seconds
Every 10 minutes
Every hour
Once a day
Proof of Work requires miners to:
Find a nonce that meets the target difficulty
Store user private keys
Modify previous blocks
Decrypt messages
A blockchain wallet stores:
Actual cryptocurrency coins
Public and private keys
Usernames and passwords
Only public keys
The longest chain rule is used to:
Increase transaction fees
Prevent forks permanently
Resolve blockchain forks
Remove miners from the network
To improve privacy, Bitcoin users often:
Reuse the same public key
Hide all transactions
Generate new key pairs for each transaction
Disable blockchain viewing
In a race attack, the attacker:
Mines a private chain
Sends the same coin to different vendors quickly
Uses stolen hardware
Alters previous blocks
The Finney attack requires the attacker to be:
A regular user
A vendor
A miner
A wallet service provider
Why is a 51% attack impractical on Bitcoin?
Users will block it
The cost of computing power is extremely high
It is illegal
It is not technically possible
Blockchain is increasingly used in supply chain management because:
It hides transaction history
It increases product costs
It improves transparency and traceability
It removes data security
