blockchain cbde practice test

What's the correct scientific notation?

• A. 1 Ether = 10^18 wei, 10^9 Gwei, 10^3 Finney
• B. 1 Ether = 10^19 wei, 10^13 Gwei, 10^3 Finney
• C. 1 Ether = 10^16 wei, 10^13 Gwei, 10^3 Finney
• D. 1 Ether = 10^18 wei, 10^6 Gwei, 10^6 Finney

What are Private Keys used for?

• A. To Protect the Public Keys by being cryptographically significant.
• B. To Sign Transactions And To Derive an Address From.
• C. To Generate An Address which can sign transactions.

Public Keys vs. Private Keys. Which statement is true?

• A. The Public Key is for Signing Transactions, the Private Key must be given out to verify the signature.
• B. The Private Key signs transactions, the Public Key can verify the signature.
• C. The Private Key is to generate a Public Key. The Public Key can sign transactions, the address is here to verify the transactions.

Proof of Work (PoW) vs. Proof of Stake.

• A. PoW is computationally intensive which requires lots of energy. On the other hand, miners earn straightforward a reward for mining a block and incorporating transactions.
• B. PoW is better than PoS, because with PoS we increase the amount of energy spent on the network.
• C. PoS is mining with specialized new hardware that has to be purchased with a stack of Ether in the network. Hence the Name: Proof of Stake, which derives from Stack.

Externally Owned Accounts:

• A. can be destroyed using the selfdestruct keyword. This way all remaining ether will be sent to the receiver address, regardless if they have a fallback function or not.
• B. are bound to a private key which is necessary to sign transactions outgoing from that account.
• C. are logical opcodes running on the ethereum blockchain very similar to smart contracts.

Smart Contracts:

• A. are always living on the same address, because the blockchain is deterministic. So, one account can always have one smart contract.
• B. are having the same address as the EOA.
• C. are sitting on their own address. The Address is created from the nonce and the EOA address and could be known in advance before deploying the smart contract.
• D. the address of the smart contract is a random address which gets generated by the miner who mines the contract-creation transaction.

Transactions containing the same data to create the same smart contract are:

• A. always having the same signature.
• B. having a different signature because of the nonce which changes upon every transaction.

Sending one Ether is actually internally translated:

• A. to Wei, so it will send the equivalent of 10^18 Wei.
• B. to Finney, so it will send the equivalent of 10^3 Finney.
• C. to Szabo, so it will send the equivalent of 10^6 Szabo.

Hashing Mining uses:

• A. Keccack256 while internally to hash values it's easy to use the Dagger-Hashimoto to create a meaningful hash.
• B. the Dagger-Hashimoto hashing while internally the EVM uses SHA256 which is an alias for Keccack256.
• C. the Dagger-Hashimoto hashing while internally the EVM uses Keccack256 which is almost similar to SHA256, but has a different padding so produces different hashes.

PoS:

• A. would be better, because it can reduce the amount of energy needed for mining.
• B. would be worse, because it would increase the amount of energy needed for mining.