CBE Foundational Concepts 5 — Questions and Answers
Question 1: What is the maximum total supply of bitcoin?
- 18 million
- 100 million
- 21 million (Correct answer)
- Unlimited
Correct answer: 21 million
Bitcoin's protocol caps the total supply at 21 million coins.
Question 2: How often does Bitcoin's block subsidy halve?
- Every 210,000 blocks (Correct answer)
- Every 2,016 blocks
- Every 100,000 blocks
- Every year
Correct answer: Every 210,000 blocks
The block reward halves every 210,000 blocks, about every four years.
Question 3: In September 2022, Ethereum moved from Proof-of-Work to Proof-of-Stake. What is this event called?
- The Fork
- The Halving
- Constantinople
- The Merge (Correct answer)
Correct answer: The Merge
The Merge joined Ethereum's execution layer with the Beacon Chain and switched it to Proof-of-Stake.
Question 4: What does a 51% attack let an attacker do?
- Steal private keys from any wallet
- Reorganize recent blocks and double-spend their own coins (Correct answer)
- Create coins beyond the supply cap
- Change other users' transaction signatures
Correct answer: Reorganize recent blocks and double-spend their own coins
Majority hash power lets an attacker rewrite recent history to double-spend, but not forge signatures or break supply rules.
Question 5: Which hash function does Ethereum mainly use?
- MD5
- SHA-1
- Keccak-256 (Correct answer)
- Scrypt
Correct answer: Keccak-256
Ethereum uses Keccak-256, a variant of the SHA-3 family, for addresses and hashing.
Question 6: What does a mnemonic seed phrase (BIP-39) represent?
- A human-readable backup that can regenerate a wallet's private keys (Correct answer)
- A public address for receiving funds
- A one-time transaction ID
- A password for an exchange account
Correct answer: A human-readable backup that can regenerate a wallet's private keys
The 12- or 24-word seed phrase encodes the master seed from which all of the wallet's keys are derived.
Question 7: Which feature of blockchain makes it hard to alter past records without detection?
- Each block includes the previous block's hash, so changing one block breaks every later link (Correct answer)
- Blocks are encrypted with AES
- All data is stored on one central server
- Transactions are deleted after confirmation
Correct answer: Each block includes the previous block's hash, so changing one block breaks every later link
Hash-linking means tampering with any block invalidates every block after it.
CBE Foundational Concepts 5
What is the maximum total supply of bitcoin?