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ED (Ethereum Developer) (CERT-ED) Exam ,
covering Ethereum architecture, smart contract
development (Solidity), Web3.js/ethers.js,
development tools (Truffle, Hardhat), Ethereum
Virtual Machine (EVM), gas optimization,
security (reentrancy, front‑running), ERC
standards (ERC‑20, ERC‑721, ERC‑1155),
decentralized applications (dApps), layer‑ 2
scaling, and deployment to mainnet/testnets.
Each question is immediately followed by the correct answer and a concise explanation referencing Ethereum yellow paper, Solidity documentation, and common exam topics.
ED (Ethereum Developer) (CERT-ED) – Practice Exam – 250 MCQs
(Unbridged)
### SECTION 1: ETHEREUM FUNDAMENTALS & ARCHITECTURE
(Q1–30)
Q1. Ethereum is best described as: A) A decentralized, open‑source blockchain with smart contract functionality B) A centralized database C) A digital currency only D) A private enterprise network Correct Answer: A Explanation: Ethereum is a decentralized platform that runs smart contracts and decentralized applications (dApps). Q2. What is the native cryptocurrency of the Ethereum network? A) Ether (ETH) B) Bitcoin (BTC) C) Solana (SOL) D) Cardano (ADA) Correct Answer: A
Correct Answer: A Explanation: Ethereum transitioned to Proof‑of‑Stake in September 2022 (the Merge). Q5. The “Beacon Chain” is responsible for: A) Coordinating Proof‑of‑Stake consensus (validators, attestations, slots, epochs) B) Executing transactions C) Storing smart contract code D) Managing token balances Correct Answer: A Explanation: The Beacon Chain runs the PoS consensus layer; execution layer handles transactions. Q6. “Gas” in Ethereum refers to: A) The unit of computational effort required to execute operations (paid in gwei) B) The price of Ether C) The block reward D) The transaction nonce
Correct Answer: A Explanation: Each EVM operation consumes a specific amount of gas; gas price is set by the user. Q7. “gwei” is: A) A denomination of Ether (1 gwei = 10⁻⁹ ETH) B) The gas limit C) The block number D) A cryptographic hash Correct Answer: A Explanation: Gas prices are typically quoted in gwei. Q8. The “base fee” in EIP‑1559 is: A) A minimum fee per gas that is burned (not paid to validators) B) The priority fee (tip) to validators C) The total transaction fee D) The block reward
Correct Answer: A Explanation: Transaction nonce must increment sequentially. Q11. “State trie” (Merkle Patricia Trie) in Ethereum stores: A) Current account balances, contract code, and storage roots B) Transaction history only C) Block headers only D) Uncles Correct Answer: A Explanation: The world state is stored in a Merkle Patricia Trie. Q12. A “block” in Ethereum contains: A) Header (parent hash, state root, transactions root, etc.), transactions, and uncles (PoW legacy) B) Only transactions C) Only the block hash D) Only the timestamp
Correct Answer: A Explanation: Blocks include headers and transaction lists. Q13. The “gas limit” (block gas limit) is: A) The maximum amount of gas allowed in a block (limits block size) B) The maximum gas a transaction can use C) The gas price D) The reward per block Correct Answer: A Explanation: Block gas limit (≈30 million) determines how many transactions fit. Q14. A “node” on the Ethereum network can be: A) Full node (stores entire blockchain and verifies), light node (header‑only), or archive node (full history) B) Only full node C) Only light node D) Only validator node Correct Answer: A
Explanation: ERC‑20 defines a standard interface for fungible tokens. Q17. ERC‑721 defines: A) Non‑fungible tokens (NFTs) B) Fungible tokens C) Semi‑fungible tokens D) Token approvals Correct Answer: A Explanation: ERC‑721 is the NFT standard. Q18. ERC‑1155 (multi‑token standard) allows: A) A single contract to manage multiple token types (fungible, non‑fungible, semi‑fungible) B) Only fungible tokens C) Only NFTs D) Only approvals Correct Answer: A
Explanation: ERC‑1155 is efficient for batch transfers. Q19. The “difficulty” bomb (now deprecated after the Merge) was used to: A) Encourage the transition to PoS by making PoW mining harder B) Increase security C) Reduce block time D) Increase gas limit Correct Answer: A Explanation: The difficulty bomb was part of the transition plan. Q20. “MEV” (Maximal Extractable Value) refers to: A) The value that validators (or searchers) can extract by reordering, including, or excluding transactions within a block B) The gas price C) The block reward D) The transaction fee Correct Answer: A
Correct Answer: A Explanation: L2s inherit security from Ethereum while increasing scalability. Q23. “Rollups” (optimistic rollups, ZK‑rollups) are a type of L2 that: A) Batch transactions and post compressed data (or validity proofs) to L B) Store data only on L C) Only handle payments D) Are not compatible with EVM Correct Answer: A Explanation: Rollups are the most promising scaling solution. Q24. “ZK‑rollups” use: A) Validity proofs (ZK‑SNARKs/STARKs) to verify batches (instant finality) B) Fraud proofs (optimistic rollups) C) No proofs D) Only off‑chain execution
Correct Answer: A Explanation: ZK‑rollups offer faster finality than optimistic rollups. Q25. “Optimistic rollups” assume transactions are valid unless challenged (fraud proof window). A) True B) False Correct Answer: A Explanation: Optimistic rollups have a challenge period (e.g., 7 days). Q26. “Sidechains” (e.g., Polygon PoS) have their own consensus mechanism and are: A) Not fully secured by Ethereum (they are separate chains) B) Fully secured by Ethereum C) L2 rollups D) Only for NFTs Correct Answer: A Explanation: Sidechains have weaker security guarantees than rollups.
Q29. A “contract account” (smart contract) is: A) Controlled by its code (no private key) B) Controlled by a private key C) Always immutable D) Only for tokens Correct Answer: A Explanation: Contract accounts have code and storage. Q30. “Precompiled contracts” (e.g., ecrecover, sha256) are: A) Built‑in EVM contracts for cryptographic operations (gas efficient) B) User‑written contracts C) ERC standards D) Transaction types Correct Answer: A Explanation: Precompiles are native EVM functions.
SECTION 2: SOLIDITY BASICS (Q31–70)
Q31. Solidity is a: A) Statically‑typed, contract‑oriented programming language for Ethereum B) Dynamically‑typed language C) SQL query language D) JavaScript library Correct Answer: A Explanation: Solidity is the primary language for writing EVM smart contracts. Q32. A “pragma” statement (e.g., pragma solidity ^0.8.0;) specifies: A) The compiler version(s) the source file is compatible with B) The license identifier C) The contract name D) The import path Correct Answer: A Explanation: Pragmas prevent mismatched compiler versions. Q33. The uint (unsigned integer) default size is:
C) The block timestamp D) The transaction hash Correct Answer: A Explanation: msg.sender is a global variable. Q36. msg.value is: A) The amount of wei sent with the transaction (for payable functions) B) The gas price C) The block number D) The transaction nonce Correct Answer: A Explanation: msg.value is the amount of Ether attached to the call. Q37. The receive() function: A) Is called when a contract receives Ether without calldata (plain Ether transfer) B) Is called for every function call C) Is the constructor
D) Is the fallback function for non‑payable calls Correct Answer: A Explanation: receive() is a special, external, payable function. Q38. The fallback() function: A) Is called when a function signature does not match any function (and for receive if not present) B) Is the same as receive() C) Is called before every function D) Is only for upgradeable contracts Correct Answer: A Explanation: Fallback is executed for unmatched function calls or when receiving Ether if receive() is not present. Q39. view functions: A) Read state but do not modify it (no gas cost when called externally) B) Modify state C) Send Ether
