NPTEL Blockchain and its Applications Week 11 Assignment Answers 2025
1. What is Hyperledger Aries primarily used for?
a) Facilitating decentralized identity management
b) Managing cryptocurrency transactions
c) Building supply chain solutions
d) Developing blockchain consensus algorithms
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2. Which of the following is/are key jobs(s) that/those Hyperledger Aries mainly perform(s)?
a) Proof-of-Stake consensus
b) Aries can work as IIN (Interoperable Identity Network) agent
c) Verifiable credentials exchange
d) Cryptographic currency generation
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3. Which of the following does NOT pose a direct risk to the security and reliability of blockchain
operations?
a) Vulnerability to 51% attacks |
b) Compromise of private key sccurity
c) Exploitation of double-spending vulnerabilities
d) High transaction fees
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4. In what ways can high computing power/stake be misused in blockchain systems?
a) Taking control of consensus to manipulate transactions and enable double-spending
b) Temporarily accelerating block generation to disproportionately increase mining rewards
c) Compromising transaction privacy by analyzing cryptographic hashes
d) Manipulating the blockchain to censor or exclude competitors’ transactions
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5. What is the main objective of a Selfish Mining Attack in a blockchain network?
a) To increase the transaction fees by monopolizing block creation.
b) To disrupt the blockchain’s consensus by manipulating the chain’s length to gain mining rewards unfairly.
c) To control over 50% of the network’s hashing power and reverse transactions.
d) To expose private transactions by decrypting the block headers.
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6. A blockchain network has a 10-minute block interval. A miner, “Miner X,” controls 40% of the
network’s hashing power. Miner X mines a block and does not broadcast it immediately. Instead,
Miner X continues mining a second block in secret.
What is the most likely result of Miner X’s actions in this scenario?
a) Miner X’s second block will automatically become part of the blockchain, and the first block
will be always discarded.
b) Miner X’s second block will possibly create a fork in the blockchain, which will later be resolved through a chain reorganization
c) Miner X will always successfully steal the rewards of other miners on the network.
d) Miner X’s actions must cause the network to collapse due to a 51% attack.
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7. Which of the following plays the most crucial role in establishing trust in a blockchain network?
a) Encryption
b) Consensus Mechanism
c) Smart Contracts
d) Distributed Ledger
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8. Which of the following is/are primarily responsible for validating transactions in the Ethereum 2.0 blockchain (Proof of Stake)?
a) Miner
b) Validator
c) Peer-to-peer network
d) Core consensus protocol
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9. Which of the following is a potential consequence of an Eclipse Attack on a blockchain node?
a) The targeted node may mine blocks more efficiently due to controlled connections.
b) The targeted node may accept fraudulent transactions or blocks, leading to potential double-
spending.
c) The targeted node will immediately disconnect from the blockchain network to prevent further
damage.
d) The targeted node will become immune to any form of attack after the Eclipse Attack
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10. Which of the following is a common technique used by attackers in a front-running attack on decentralized exchanges (DEXs)?
a) Manipulating the gas price to prioritize their transaction over others.
b) Encrypting transactions to hide them from miners.
c) Using a 51% attack to gain control over the network.
d) Altering the smart contract code to change transaction outcomes.
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