Blockchain and its Applications | Week 4

Course Name: Blockchain and its Applications

Course Link: Click Here

These are Blockchain and its Applications Assignment 4 Answers

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Q1. “We can achieve consensus with a single crash failure in a perfect asynchronous network.” This scenario is?
a. Always true
b. Impossible
c. Can’t say
d. Sometimes true

Answer: b. Impossible

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Q2. Which is/are the example/s of a double-spending attack?
a. Anwesha has a total of 60 unspent bitcoins from two different transactions with an equal amount of bitcoins each. She sends the entire amount each to Arpita and Ankur from one of the transactions
b. Bobby bought a bike using ‘t’ bitcoins. On delivery, the bitcoins are transferred from his wallet to the shopper’s wallet. Simultaneously, he uses that bitcoins for another purchase
c. Bibhu has 140 unspent bitcoins. He sends the entire amount each to Deepak and Tanmay
d. Deepak and Bibhu each have 70 unspent bitcoins. Both of them transfer 20 bitcoins to each other

Answer: a, b, c

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These are Blockchain and its Applications Assignment 4 Answers

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Q3. What is the correct order of adding a new block to blockchain
i. Block Mining
ii. Block propagation
iii. Block Flooding
iv. Transaction Flooding
a. iii, iv, ii, i
b. iv, iii, ii, i
c. ii, i, iii, iv
d. iv, i, iii, ii

Answer: d. iv, i, iii, ii

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Q4. Double spending is reusing digital assets intentionally or inadvertently True or False?
a. True
b. False

Answer: a. True

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These are Blockchain and its Applications Assignment 4 Answers

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Q5. In the blockchain, cryptography ensures the authenticity of a transaction and also helps prevent double-spend. Is the above statement True or False?
a. True
b. False

Answer: b. False

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Q6. What are Bitcoin exchanges available in India:
i. BuyUCoin
ii. ZebPay
iii. WazirX
a. i and ii
b. ii and ii
c. i and iii
d. i, ii and iii

Answer: a, b, c, d

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These are Blockchain and its Applications Assignment 4 Answers

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Q7. The primary difference between the permissionless and permissioned blockchain is __________?
a. Access control for the participants in the blockchain network
b. Hash Algorithms
c. Confidentiality
d. Availability

Answer: a. Access control for the participants in the blockchain network

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Q8. What is an advantage of a permissionless blockchain?
a. It does not use disinterested third parties to secure blocks, as all participants have a vested interest.
b. It is more resilient against fraud because it uses federated nodes to combat fraud.
c. It is open to everyone in the world without permission and licensing requirements.
d. Its networks are built by for-profit companies and the working of the network is guaranteed.

Answer: c. It is open to everyone in the world without permission and licensing requirements.

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These are Blockchain and its Applications Assignment 4 Answers

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Q9. After a hard fork, the emerging two chains are incompatible. True or False?
a. True
b. False

Answer: a. True

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Q10. Bitcoin protocol runs over
i. TCP
ii. UDP
iii. HTTP
iv. HTTPS
a. i, ii, iii
b. i, iv
c. Only i
d. Only ii

Answer: c. Only i

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These are Blockchain and its Applications Assignment 4 Answers

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