Blockchain and its applications Q and A

  1. The transaction Merkle Tree root value in a Bitcoin block is calculated using?

a. Number of transactions

b. None

c. Previous block’s hash

d. Hash of transactions

2. Proof of work is the ________________ used by Bitcoin blockchain and Ethereum blockchain?

a. Transaction confirmation

b. Incentive function

c. Consensus Protocol

d. Trust function

3. Inspect and explore block #490624 using this link to solve the below question. What is the hash of the previous block for Bitcoin block #490624? Copy and paste the answer into the box below.

Answer – 0000000000000000004239f2a01d8f579bc0dbb214d0f874ece5db587bee3457

4. Bitcoin Scripting Language:

a. Turing Complete

b. Supports Cryptography

c. Stack Based

d. Supports infinite time/memory

5. What is nonce?

a. The number miners run through to get a correct hash

b. The transaction id number

c. A miner’s ASIC chip array

d. The generator point used in elliptic curve cryptography

6. Which of the following opcodes is needed to remove the top stack item?

a. OP_DROP

b. OP_POP

c. OP_DEQUE

d. OP_DELETE

7. Which of these fields is present in Bitcoin block summary?

a. Gas Used

b. Gas Limit

c. Difficulty

d. Private Key of the Sender

8. In bitcoin block header, the block identifier is calculated:

a. Using Double SHA256 on the Current block header

b. Using SHA256 on the current block header

c. Using Double SHA256 on the previous block hash

d. Using Double SHA256 on the Difficulty bits

9. 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

10. Which of the following Bitcoin scripts will generate a TRUE outcome?

i. scriptSig: <sig> scriptPubKey: <pubkey> OP_DUO OP_HASH256 <pubKeyHash> OP_EQUAL OP_VERIFY OP_CHECKSIG

ii. scriptSig: <pubKey> scriptPubKey: OP_HASH160 <pubKeyHash> OP_EQUAL

iii. scriptSig: <pubKey> scriptPubkey: <pubKey> OP_EQUALVERIFY

iv. scriptSig: <sig> scriptPubKey: <pubKey> OP_CHECKSIG

a. i, ii, iii

b. iii, iv

c. i, ii and iv

d. i, iii, iv

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