FREE Blockchain Developer Smart Contract Development Questions and Answers Flashcards
6 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 FREE Blockchain Developer Smart Contract Development Questions and Answers flashcards as text
What is the key difference between 'call' and 'delegatecall' in Solidity?
Answer: delegatecall executes code in the caller's context, call executes in the callee's context
With delegatecall, the called contract's code runs using the calling contract's storage, msg.sender, and msg.value, preserving the caller's execution context.
Which tool is specifically designed for formal verification of Ethereum smart contracts?
Answer: Certora Prover
Certora Prover uses formal verification techniques to mathematically prove that smart contract code satisfies specified properties and invariants.
What does the 'unchecked' block in Solidity 0.8+ do?
Answer: Disables automatic overflow and underflow checks for arithmetic operations
The 'unchecked' block disables the built-in overflow/underflow protection introduced in Solidity 0.8, saving gas when overflow is mathematically impossible.
In the ERC-721 standard, what is the purpose of the 'safeTransferFrom' function compared to 'transferFrom'?
Answer: It checks if the recipient can handle NFTs by calling onERC721Received
safeTransferFrom verifies the recipient contract implements the ERC721Receiver interface by calling onERC721Received, preventing tokens from being permanently locked in incompatible contracts.
What is a flash loan in the context of DeFi smart contracts?
Answer: An uncollateralized loan that must be borrowed and repaid within a single transaction
Flash loans allow borrowing any amount without collateral as long as the full amount plus fees is returned within the same atomic transaction.
Which storage optimization technique reduces gas costs by packing multiple small variables into a single 32-byte storage slot?
Answer: Variable packing
Variable packing arranges consecutive state variables of smaller types so the EVM can fit multiple values into one 256-bit storage slot, reducing costly SSTORE operations.