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Smart Contracts and dApps Flashcards

7 cards from real Cryptocurrency practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What is 'MEV' (Maximal Extractable Value) in blockchain networks?

    Answer: Profit extracted by reordering, inserting, or censoring transactions within a block

    MEV refers to extra profit that block producers (or searchers) can capture by manipulating the order of transactions — through front-running, sandwich attacks, or liquidation sniping.

  2. Which Layer 2 scaling solution bundles many transactions off-chain and posts a validity proof to Ethereum?

    Answer: ZK rollup

    ZK (zero-knowledge) rollups compress transactions off-chain and submit a cryptographic validity proof to Ethereum Layer 1, allowing instant finality without a fraud-proof challenge period.

  3. What is the function of 'Chainlink VRF' in smart contract development?

    Answer: It validates that randomness used in a contract is provably fair and tamper-resistant

    Chainlink VRF (Verifiable Random Function) generates random numbers with cryptographic proof that the output was not manipulated, enabling fair on-chain lotteries, NFT trait reveals, and games.

  4. In Solidity, what is the purpose of the 'payable' keyword on a function?

    Answer: It allows the function to receive ETH along with the call

    Without the 'payable' modifier, a Solidity function will revert if ETH is sent to it; adding 'payable' lets the function accept and hold incoming ETH.

  5. What is a 'timelock controller' commonly used for in DeFi protocols?

    Answer: Delaying execution of governance decisions to give users time to react or exit

    A timelock enforces a mandatory waiting period between a proposal passing and its on-chain execution, giving the community and security researchers a window to detect and respond to malicious changes.

  6. What does the acronym 'dApp' stand for?

    Answer: Decentralized Application

    A decentralized application (dApp) runs its backend logic on a decentralized network (typically smart contracts on a blockchain) rather than centralized servers.

  7. What is 'liquidity mining' (also called yield farming) in DeFi?

    Answer: Earning protocol governance tokens as rewards for supplying liquidity to a DeFi platform

    Liquidity mining incentivizes users to deposit assets into DeFi protocols by distributing native governance tokens as additional yield on top of trading fees.