Blockchain and its Applications Assignment 3 Answers (JAN-APR 2025)
1) If the current block reward for Bitcoin is 6.25 BTC, and the difficulty adjustment mechanism is such that, on average, a new block is found every 10 minutes, how much Bitcoin will be mined per day (24 hours)? a) 75 BTC b) 144 BTC c) 900 BTC d) 1,080 BTC
2) Which of the following best defines a permissioned blockchain? a) Anyone can join and validate transactions without approval. b) Only authorized participants can write and validate transactions. c) It always uses proof-of-work (PoW) for consensus. d) A permissioned blockchain does not need cryptographic hash operations.
3) Which of the following combinations is correctly used to compute Bitcoin’s current block hash? a) Previous block’s hash, Merkle root, block reward, nonce, timestamp, and block size b) Previous block’s hash, timestamp, nonce, Merkle root, difficulty bits, and block version c) Block creator’s public key, Merkle root, timestamp, block reward, nonce, and difficulty level d) Previous block’s hash, nonce, Merkle root, height, timestamp, and difficulty bits
4) Which of the following difficulty targets would make it most difficult for miners to find a valid block? a) 0000000000000000000000000000000000000000000000000000000000056789abcdef123 b) 000000000000000000000000000000000000000000000000000000002dfe34a1b2c3d555 c) 00000000000000000000000000000000000000000000000000000000000afc123987abc d) 00000000000000000000000000000000000000000000000000000000000000000af46789
5) In Bitcoin, what does the block identifier refer to? a) SHA1 (128 bits) of the future block header b) Double SHA256 of the current block header c) Double SHA256 of the difficulty bits only d) Triple SHA256 of the future block header
6) In a Merkle tree with n transactions (where n is a power of 2), if one transaction is invalid, how many recalculations are needed to detect and correct the invalid transaction? a) n/2 b) log₂(n) + 7 c) 3log₂(n)
9) What is a nonce in the context of Bitcoin mining? a) The transaction ID number b) A miner’s ASIC chip array c) The generator point used in elliptic curve cryptography d) A value miners iterate through to generate a valid hash
10) What happens if the number of transactions in a Merkle tree is odd? a) The tree cannot be built b) Dummy (duplicate) hashes are added to adjust c) Transactions are left out of the block d) The Merkle root is ignored
Blockchain and its Applications Assignment 3 Answers (JAN-APR 2024)
Q1. Inspect and explore block #828070 using this link to solve the below question. What is the hash of the previous block for Bitcoin block #828070?
Answer: a
Q2. Which of the following Python scripts will generate a TRUE outcome? a. scriptSig: scriptPubKey: OP_DUP OP_HASH256 OP_EQUAL OP_VERIFY OP_CHECKSIG b. scriptSig: scriptPubKey: OP_HASH160 OP_EQUAL c. scriptSig: scriptPubKey: OP_EQUALVERIFY d. scriptSig: scriptPubKey: OP_CHECKSIG
Answer: c. scriptSig: scriptPubKey: OP_EQUALVERIFY
These are Blockchain and its Applications Assignment 3 Answers
Q3. In the Bitcoin block header, the block identifier is calculated a. Using SHA256 on the current block header b. Using Double SHA256 on the previous block hash c. Using Double SHA256 on the Difficulty bits d. Using Double SHA256 on the current block header
Answer: d. Using Double SHA256 on the current block header
Q4. If the six-byte difficulty bits in the hexadecimal form are 0x1a05f20881ab, and the target value is calculated using X* 2^(Y), what are the values for X and Y respectively? a. X = 0x5f20881ab, Y = 0x1a b. X = 0x1a05f2, Y = 0x0881ab c. X = 0x1a05f2, Y = 0x18 d. X = 0x5f20881ab, Y = 0x1a0
Answer: a. X = 0x5f20881ab, Y = 0x1a
These are Blockchain and its Applications Assignment 3 Answers
Q5. DLT can be used to maintain financial information only. a. False b. True
Answer: a. False
Q6. Which one of the following opcodes is needed to remove the second-to-top stack item? a. OP_DELETE b. OP_2POP c. OP_DEQUE d. OP_NIP
These are Blockchain and its Applications Assignment 3 Answers
Q7. Bitcoin Scripting Language: a. Not Turing Complete b. Supports Cryptography C. Queue Based d. Supports infinite time/memory
Answer: a, b
Q8. Permissioned blockchain is regarded as more secure than open blockchain as the participants are known beforehand and pre-authenticated. a. True b. False
Answer: a. True
These are Blockchain and its Applications Assignment 3 Answers
Q9. What is nonce? a. The transaction ID number b. A miner ASIC chip array C. The generator point used in elliptic curve cryptography d. The number miners run through to generate a correct hash
Answer: d. The number miners run through to generate a correct hash
Q10. Which of these fields is present in a Bitcoin block summary? a. Nonce b. Gas Used c. Gas Limit d. Private Key of the Sender
Blockchain and its Applications Assignment 3 Answers ( JAN-APR 2022 )
Q1. Bitcoin mining is performed by a. Miner nodes b. Internal Nodes c. External Nodes d. Orphan Nodes
Answer: a. Miner nodes
Q2. DLT can be used to maintain financial information only. a. False b. True
Answer: a. False
These are Blockchain and its Applications Assignment 3 Answers
Q3. Which of the following is/are true for basic PoW consensus? a. Miner needs to propose a block b. The miner needs to solve a puzzle to obtain target block hash c. The puzzle solution is added as proof for leadership d. Successful miner node is rewarded
Answer: a, b, c, d
Q4. Bitcoin Scripting Language: a. Not Turing Complete b. Supports Cryptography c. Stack Based d. Supports infinite time/memory
Answer: a, b, c
These are Blockchain and its Applications Assignment 3 Answers
Q5. Permissioned blockchain is regarded as more secure than open blockchain as the participants are known beforehand and pre-authenticated. a. True b. False
Answer: a
Q6. What is nonce? a. The transaction id number b. A miners ASIC chip array c. The generator point used in elliptic curve cryptography d. The number miners run through to generate a correct hash
Answer: d. The number miners run through to generate a correct hash
These are Blockchain and its Applications Assignment 3 Answers
Q7. Which one of the following opcodes is needed to remove the top stack item. a. OP POP b. OP_DEQUE c. OP DROP d. OP DELETE
Answer: c. OP DROP
Q8. Which of these fields is present in a Bitcoin block summary? a. Difficulty b. Gas Used c. Gas Limit d. Private Key of the Sender
Answer: a. Difficulty
These are Blockchain and its Applications Assignment 3 Answers
Q9. If the four-byte difficulty bits in hex form are 0x1b0404cb, and the target value is calculated using X* 2^(Y), what is the values for X and Y respectively, a. X = 0x0404cb, Y = 0x1b b. X = 0x0404cb, Y = 0x18 c. X = 0x0404cb, Y = 0xc0 d. X = 0x1b0404, Y = 0xcb
Answer: c. X = 0x0404cb, Y = 0xc0
Q10. In bitcoin block header, the block identifier is calculated a. Using SHA256 on the current block header b. Using Double SHA256 on the previous block hash c. Using Double SHA256 on the Difficulty bits d. Using Double SHA256 on the current block header
Answer: d. Using Double SHA256 on the current block header
These are Blockchain and its Applications Assignment 3 Answers
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