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Sample BTA CBDE Practice Questions
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1In Ethereum, which type of account is controlled by a private key and has no associated code?
A.Contract account
B.Validator account
C.Externally owned account (EOA)
D.Storage account
Explanation: An externally owned account (EOA) is controlled by a private key, has no code, and can initiate transactions. Contract accounts have associated code and are controlled by that code.
2What is the primary purpose of gas in Ethereum?
A.To pay validator salaries directly in stablecoins
B.To measure and pay for the computational work a transaction requires
C.To set the block size limit
D.To encrypt transaction data
Explanation: Gas measures the computational effort required to execute operations. Users pay gas fees (in ether) to compensate the network for processing and to prevent infinite loops or spam.
3What does the EVM stand for and primarily do?
A.Ethereum Verification Module; it verifies signatures
B.Encrypted Value Mapping; it stores account balances
C.Ethereum Validation Mechanism; it selects block producers
D.Ethereum Virtual Machine; it executes smart contract bytecode
Explanation: The Ethereum Virtual Machine (EVM) is the runtime environment that executes compiled smart contract bytecode (opcodes) deterministically across all nodes.
4What is the native word size of the Ethereum Virtual Machine?
A.32 bits
B.256 bits
C.64 bits
D.128 bits
Explanation: The EVM operates on 256-bit (32-byte) words. This size was chosen to work efficiently with 256-bit cryptography such as Keccak-256 hashing and secp256k1 signatures.
5What is the purpose of the nonce in an Ethereum externally owned account?
A.It stores the account's ether balance
B.It counts the number of transactions sent from the account, preventing replay and ordering transactions
C.It holds the contract's bytecode hash
D.It records the gas price of the last transaction
Explanation: For an EOA, the nonce is the count of transactions sent from that account. It ensures transactions are processed in order and prevents the same transaction from being replayed.
6What consensus mechanism does Ethereum use after The Merge (2022)?
A.Proof of Work
B.Proof of Authority
C.Proof of Stake
D.Delegated Proof of Stake
Explanation: After The Merge in September 2022, Ethereum transitioned from Proof of Work to Proof of Stake, where validators stake ETH to propose and attest to blocks.
7What is the smallest denomination of ether?
A.Gwei
B.Wei
C.Finney
D.Szabo
Explanation: Wei is the smallest unit of ether; 1 ether equals 10^18 wei. Gwei (10^9 wei) is commonly used for expressing gas prices.
8In the EIP-1559 fee model, what happens to the base fee paid by users?
A.It is paid entirely to the block proposer
B.It is locked in a treasury contract
C.It is burned (removed from circulation)
D.It is refunded after 256 blocks
Explanation: Under EIP-1559, the base fee is algorithmically set per block and is burned, while users can add a priority fee (tip) that goes to the validator/proposer.
9Which hashing algorithm does Ethereum primarily use for addresses and state?
A.SHA-256
B.RIPEMD-160
C.Blake2b
D.Keccak-256
Explanation: Ethereum uses Keccak-256 (often loosely called SHA-3) for hashing. Addresses are derived from the last 20 bytes of the Keccak-256 hash of the public key.
10What is the length of a standard Ethereum address?
A.32 bytes (64 hex characters)
B.16 bytes (32 hex characters)
C.20 bytes (40 hex characters)
D.64 bytes (128 hex characters)
Explanation: An Ethereum address is 20 bytes, displayed as 40 hexadecimal characters prefixed with 0x. It is derived from the last 20 bytes of the Keccak-256 hash of the account's public key.
About the BTA CBDE Practice Questions
Verified exam format metadata for Certified Blockchain Developer — Ethereum is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.