Blockchain and its Applications Nptel Assignment 5 Answers
Course Name: Blockchain and its Applications
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Table of Contents
Blockchain and its Applications Assignment 5 Answers (JAN-APR 2025)
- What is/are the limitations of using the consensus algorithm Proof of Work (PoW)?
a. A lot of mining power is wasted as only one gets success in mining at a time
b. PoW is typically used for permissioned blockchain
c. It is used for blockchain mining
d. High costs and difficulty in supporting large-scale adoption
- Which of the following is/are not applicable for PoET (Proof of Elapsed Time) consensus?
a. Each participant in the blockchain network waits a random amount of time
b. The first participant to finish becomes the follower for the new block
c. Trusted execution platform and attestation are used to verify that the proposer has really waited
d. The first participant to finish becomes the leader for the new block
- How can an attacker manipulate the transaction history of an existing blockchain whose ledger cannot be modified, only appended?
a. The attacker hard-forked the network and created a new blockchain network.
b. The attacker modified the smart contract and recovered the investor’s cryptocurrency.
c. The attacker gained control of more than 51% of the network’s computing power.
d. The attacker gained control of less than 49% of the network’s computing power.
- What is the role of the Ethereum Virtual Machine (EVM)?
a. To directly connect the Ethereum nodes
b. To execute smart contracts in a decentralized manner
c. To directly mine blocks
d. To disrupt the Ethereum network and cause failures
- Which of the following syntax is correct to write data in a smart contract using Solidity?
a.myContract.methods.store("10").set()
b.myContract.methods.write("10").send()
c.myContract.methods.store("10").send()
d.myContract.methods.write("10").set()
- 2.5 ether equals
a. 2.5 × 10⁸ Gwei
b. 2.5 × 10¹⁰ Gwei
c. 2.5 × 10⁷ Gwei
d. 2.5 × 10⁹ Gwei
- Which JSON-RPC method is used to query the balance of an Ethereum account?
a.eth_sendTransaction
b.eth_getBalance
c.eth_getBlockByNumber
d.eth_getTransactionByHash
- What parameter in an Ethereum transaction specifies the fee for computational resources required?
a. Gas
b. Nonce
c. Data
d. Value
- Which consensus algorithm requires miners to show proof of sending coins to a verifiably un-spendable address?
a. Proof of Work (PoW)
b. Proof of Stake (PoS)
c. Proof of Burn (PoB)
d. Proof of Elapsed Time (PoET)
- What is the main difference between PoS (Proof of Stake) and PoW (Proof of Work)?
a. PoS requires computational work; PoW requires a stake.
b. PoS relies on the stake held by miners; PoW relies on computational power.
c. PoS consumes external resources; PoW consumes virtual resources.
d. PoS eliminates the need for block validation.
Blockchain and its Applications Assignment 5 Answers (JAN-APR 2024)
Q1. The height of the block is the in the chain between it and the genesis block.
a. Metafiles
b. Hash
c. Log size
d. Number of blocks
Answer: d. Number of blocks
Q2. What is the CLI command used to send ethers after the nodes have been initialized?
a. eth.submitTransaction()
b. eth.sendTransaction()
c. eth.sendIBANTransaction()
d. eth.sendRawTransaction()
Answer: b. eth.sendTransaction()
These are Blockchain and its Applications Assignment 5 Answers
Q3. Which of the following syntax is correct to write data in a smart contract using solidity
a. myContract.methods.store(“55”).set()
b. myContract.methods.write(“55”).send()
c. myContract.methods.store(“55”).send()
d. myContract.methods.write(“55”).set()
Answer: c. myContract.methods.store(“55”).send()
Q4. What is the limitation of using the consensus algorithm Proof of Work (POW)?
a. A lot of mining power is wasted as only one gets success in mining at a time
b. PoW is used for permissioned blockchain
c. It is used for blockchain mining
d. High transaction throughput
Answer: a. A lot of mining power is wasted as only one gets success in mining at a time
These are Blockchain and its Applications Assignment 5 Answers
Q5. Which statement(s) is/are true for PoS(Proof of Stake) consensus?
a. Depends on the work done by the miner
b. Depends on the amount of crypto currency the miner holds
c. Provides less protection in general
d. None of the above
Answer: b. Depends on the amount of crypto currency the miner holds
Q6. Which of the following is/are applicable for PoET (Proof of Elapsed Time) consensus
a. Each participant in the blockchain network waits a random amount of time
b. The first participant to finish becomes the follower for the new block
c. Trusted execution platform and attestation are used to verify that the proposer has really waited
d. The first participant to finish becomes the leader for the new block.
Answer: a, c, d
These are Blockchain and its Applications Assignment 5 Answers
Q7. Proof of Burn consensus algorithms also consider virtual resources or digital coins for participating in the mining activity?
a. True
b. False
Answer: a. True
Q8. 15 ether equals
a. 15X(1016) wei
b. 15X(10^18) wei
c. 15X(10^6) wei
d. 15X(10^8) wei
Answer: b. 15X(10^18) wei
These are Blockchain and its Applications Assignment 5 Answers
Q9. How an attacker could manipulate the transaction history of an existing blockchain
a. The attacker hard-forked the network and created a new blockchain network.
b. The attacker modified the smart contract and recovered the investor’s cryptocurrency.
c. The attacker gained control of more than 51% of the network’s computing power.
d. The attacker gained control of less than 49% of the network’s computing power.
Answer: c. The attacker gained control of more than 51% of the network’s computing power.
Q10. What library/API is used for smart contract deployment and invocation from Dapp?
a. Contract
b. web3
c. admin
d. eth
Answer: b. web3
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These are Blockchain and its Applications Assignment 5 Answers
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Course Name: Blockchain and its Applications
Course Link: Click Here
Blockchain and its Applications Assignment 5 Answers (JAN-APR 2022)
Q1. What is the limitation of using the consensus algorithm Proof of Work (POW)?
a. A lot of mining power is wasted as only one gets success in mining at a time
b. PoW is used for permissioned blockchain
c. Low transaction throughput
d. It is used for blockchain mining
Answer: a, c
Q2. Which statement(s) is/are true for PoS(Proof of Stake) consensus?
a. Depends on the work done by the miner
b. Depends on the amount of crypto currency the miner holds
c. Provides less protection in general
d. None of the above
Answer: b. Depends on the amount of crypto currency the miner holds
These are Blockchain and its Applications Assignment 5 Answers
Q3. Which of the following is/are applicable for POET(Proof of Elapsed Time) consensus
a. Each participant in the blockchain network waits a random amount of time
b. The first participant to finish becomes the leader for the new block
c. Trusted execution platform and attestation are used to verify that the proposer has really waited
d. None of the above.
Answer: a, b, c
Q4. Proof of Burn consensus algorithms do not consider virtual resources or digital coins for participating in the mining activity?
a. True
b. False
Answer: b. False
These are Blockchain and its Applications Assignment 5 Answers
Q5. 5 ether equals
a. 5X(10^16) wei
b. 5X(10^8) wei
c. 5X(10^6) wei
d. 5X(10^18) wei
Answer: d. 5X(10^18) wei
Q6. Which of the following syntax is correct to write data in a smart contract using solidity
a. myContract.methods.store(“99”).set()
b. myContract.methods.store(“99”).send()
c. myContract.methods.write(“99”).send()
d. myContract.methods.write(“99”).set()
Answer: b. myContract.methods.store(“99”).send()
These are Blockchain and its Applications Assignment 5 Answers
Q7. How an attacker could manipulate the transaction history of a blockchain to be able to spend a token or a cryptocurrency twice.
a. The attacker hard-forked the network and created a new blockchain network.
b. The attacker modified the transaction on his node and propagated it in the network.
c. The attacker modified the smart contract and recovered the investor’s cryptocurrency.
d. The attacker gained control of more than 51% of the network’s computing power.
Answer: d. The attacker gained control of more than 51% of the network’s computing power.
Q8. What library/API is used for smart contract deployment and invocation from Dapp?
a. Contract
b. web3
c. admin
d. eth
Answer: b. web3
These are Blockchain and its Applications Assignment 5 Answers
Q9. What is the CLI command used to send ethers after the nodes have been initialized?
a. eth.submit Transaction()
b. eth.sendIBANTransaction()
c. eth.sendRawTransaction()
d. eth.sendTransaction()
Answer: d. eth.sendTransaction()
Q10. In which scenario is a smart contract the best solution to the problem?
a. A restaurant manager wants to force customers to pay for their food by transferring cryptocurrency to his wallet.
b. A chief engineer wants her smart watch to notify her when her partner enters their front door.
c. A grid company wants to automatically buy power when the price reaches a predetermined rate.
d. An insurance company wants to pay out a small vendor whenever the case manager feels it is best to do so.
Answer: c. A grid company wants to automatically buy power when the price reaches a predetermined rate.
These are Blockchain and its Applications Assignment 5 Answers
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