Ethereum Architecture and Transaction Lifecycle BBLC Practice Questions (Page 6)

Questions 26–30

1. 26foundation · easy

   What is the first thing a node checks when validating an incoming transaction?

   • AWhether the transaction data is encrypted
   • BWhether the sender's nonce matches the expected next nonce for that account
   • CWhether the transaction was broadcast by a trusted node
   • DWhether the recipient contract has enough storage
   Reveal Solution Discussion Select an answer first
2. 27foundation · easy

   In Ethereum's proof-of-stake consensus, what is the role of validators in finalizing a block?

   • AValidators store the entire blockchain and serve it to users
   • BValidators solve complex mathematical puzzles to add blocks
   • CValidators attest to the validity of blocks, and blocks with sufficient attestations become finalized
   • DValidators vote on every transaction individually
   Reveal Solution Discussion Select an answer first
4. 28application · medium

   A developer is constructing a raw transaction to send 0.5 ETH from an EOA to a contract that will trigger a state change. The developer sets `gasLimit` to 100,000 and `gasPrice` to 20 gwei. Which additional field is REQUIRED for the transaction to be valid and executable?

   • A`blockNumber` — the block in which the transaction should be included.
   • B`nonce` — the count of transactions already sent from the sender's address.
   • C`initCode` — the bytecode to deploy a new contract.
   • D`accessList` — the list of storage keys to pre-warm.
   Reveal Solution Discussion Select an answer first
5. 29expert · hard

   A user wants to send a transaction that must be included in the next block. The network is congested, and the base fee is 50 gwei. The user sets a gas price of 60 gwei and a gas limit of 100,000. The transaction is included, but the user notices the actual fee charged is higher than expected. What is the most likely reason?

   • AThe base fee increased after the transaction was included, so the user was charged retroactively.
   • BThe transaction consumed more gas than the estimated 100,000, so the gas limit was exceeded and the transaction reverted.
   • CThe wallet automatically increased the gas price to ensure inclusion, and the user was charged the higher price.
   • DThe user set a priority fee (tip) that is added to the base fee, increasing the total gas price.
   Reveal Solution Discussion Select an answer first
6. 30foundation · easy

   How are transactions grouped into blocks on Ethereum?

   • ATransactions are grouped by the smart contract they interact with
   • BTransactions are grouped by the network automatically based on their timestamps
   • CA block producer (miner or validator) selects pending transactions from the mempool and orders them into a block
   • DTransactions are grouped by the sender's address in alphabetical order
   Reveal Solution Discussion Select an answer first