Blockchain

What fundamental problem does blockchain technology solve?. Data storage limitations. The double-spending problem without central authority. Internet connectivity issues. Encryption weaknesses.

Who is credited with creating Bitcoin and publishing the Bitcoin whitepaper?. Vitalik Buterin. Nick Szabo. Satoshi Nakamoto. Gavin Wood.

What is the primary difference between centralized and decentralized systems?. Centralized systems are faster, decentralized systems are slower. Centralized systems have a single point of control, decentralized systems distribute control. Centralized systems use blockchain, decentralized systems don't. Centralized systems are always more secure.

Which of the following is NOT a characteristic of commodity money?. Durability. Government decree as the sole source of value. Portability. Divisibility.

What event in 1971 fundamentally changed the global monetary system?. The creation of the Euro. The Bretton Woods Agreement. President Nixon suspending dollar convertibility to gold. The establishment of the Federal Reserve.

In public-key cryptography used in blockchain, what is the relationship between public and private keys?. They are identical. The private key can be derived from the public key. The public key is derived from the private key, but the reverse is computationally infeasible. They are unrelated.

What is the primary purpose of a digital signature in blockchain?. Encrypt transaction data. Prove ownership and authorize transfers without revealing the private key. Compress transaction data. Generate new addresses.

Which hash function does Bitcoin primarily use?. SHA-256. Keccak-256. MD5. RIPEMD-160.

What is a Merkle tree primarily used for in blockchain?. Encrypting transactions. Efficient verification of transaction inclusion in a block. Generating private keys. Consensus among nodes.

What is the mempool in blockchain networks?. A memory pool of confirmed transactions. A node's local collection of valid but unconfirmed transactions. The main blockchain database. A mining reward calculation tool.

What does a transaction's "confirmation" mean?. The transaction has been signed. The transaction has been broadcast to the network. The transaction has been included in a block. The transaction has been encrypted.

In the UTXO model, what does UTXO stand for?. Unified Transaction Xchange Output. Unspent Transaction Output. Universal Token Xfer Operation. Unconfirmed Transaction XOR.

What is the Byzantine Generals Problem?. A military strategy game. A problem of achieving agreement among distributed participants despite faulty or malicious actors. A encryption algorithm. A networking protocol.

In Bitcoin mining, what is the nonce?. The transaction fee. A number varied during mining to achieve a valid block hash. The block reward. The miner's signature.

How often does Bitcoin adjust its mining difficulty?. Every block. Every 24 hours. Every 2016 blocks (approximately two weeks). Every month.

What is the maximum supply of Bitcoin that will ever exist?. 100 million. 1 billion. 21 million. Unlimited.

In Proof of Stake systems, what is slashing?. Reducing block times. Destroying part of a validator's stake as penalty for misbehavior. Splitting the blockchain. Increasing transaction fees.

What was "The Merge" in Ethereum's history?. A merger of two cryptocurrencies. Ethereum's transition from Proof of Work to Proof of Stake. Combining Ethereum and Bitcoin networks. A smart contract upgrade.

Which consensus mechanism requires validators to lock up tokens as collateral?. Proof of Work. Proof of Stake. Proof of Authority. Proof of Elapsed Time.

What is the approximate energy reduction achieved by Ethereum's transition to Proof of Stake?. 50%. 75%. 99%. 25%.

Which type of blockchain allows anyone to participate without permission?. Private blockchain. Consortium blockchain. Public blockchain. Federated blockchain.

What is a consortium blockchain?. A blockchain controlled by a single organization. A blockchain jointly governed by multiple organizations. A completely public blockchain. A blockchain with no consensus mechanism.

Which platform is an example of an enterprise-grade permissioned blockchain framework?. Bitcoin. Ethereum. Hyperledger Fabric. Solana.

What is a "channel" in Hyperledger Fabric?. A communication protocol. A private sub-network allowing specific groups to transact privately. A consensus mechanism. A type of smart contract.

How many validators participate in Binance Smart Chain's consensus at any time?. 100. 21. 1000. Unlimited.

What is the primary advantage of EVM compatibility?. Faster transaction speeds. Developers can deploy Ethereum-based dApps on other chains with minimal modification. Better security. Lower energy consumption.

Walmart's Food Trust network, which reduced food traceability from 7 days to 2.2 seconds, is built on which platform?. Bitcoin. Ethereum. Hyperledger Fabric. Binance Smart Chain.

Who coined the term "smart contract" in the 1990s?. Satoshi Nakamoto. Vitalik Buterin. Nick Szabo. Gavin Wood.

What is a smart contract?. A legal document stored on blockchain. A self-executing program on blockchain that automatically enforces agreement terms. A cryptocurrency wallet. A mining algorithm.

Why must smart contract execution be deterministic?. To make it faster. So all nodes reach identical results and maintain consensus. To reduce gas costs. To enable encryption.

What is gas in Ethereum?. The fuel for mining hardware. A unit measuring computational work, with each operation consuming gas. A type of token. A consensus mechanism.

Which EIP reformed Ethereum's fee market by introducing base fee burning?. EIP-1559. EIP-20. EIP-721. EIP-1014.

What is the primary purpose of the Ethereum Virtual Machine (EVM)?. To mine ether. The runtime environment executing smart contract bytecode. To store transaction data. To generate private keys.

Which of the following operations costs the most gas?. ADD (addition). MUL (multiplication). SSTORE (storage write). BALANCE (check balance).

What is the role of an oracle in blockchain?. To predict future prices. To bring external data onto the blockchain deterministically. To mine blocks. To validate transactions.

The double-spending problem only affects digital currencies, not physical money. True. False.

Fiat currency is backed by a physical commodity like gold. True. False.

Satoshi Nakamoto's true identity has been conclusively proven. True. False.

Centralized systems have no single point of failure. True. False.

Blockchain technology enables digital scarcity. True. False.

A private key can be derived from its corresponding public key. True. False.

Digital signatures in blockchain prove ownership without revealing the private key. True. False.

SHA-256 produces a 512-bit output. True. False.

A Merkle root summarizes all transactions in a block with a single hash. True. False.

The mempool is the same across all nodes in the network. True. False.

A transaction with 6 confirmations on Bitcoin is mathematically certain and irreversible. True. False.

In the UTXO model , your balance is the sum of all UTXOs you can spend. True. False.

Proof of Work achieves consensus through computational competition. True. False.

Bitcoin's difficulty adjusts after every block. True. False.

Proof of Stake validators risk their own capital and can be slashed for misbehavior. True. False.

Ethereum's transition to Proof of Stake increased energy consumption. True. False.

The Byzantine Generals Problem is irrelevant to blockchain consensus. True. False.

In Proof of Stake, validators are selected randomly with probability proportional to their stake. True. False.

Bitcoin's maximum supply is capped at 21 million coins. True. False.

Public blockchains require permission to participate. True. False.

Private blockchains are controlled by a single organization. True. False.

Consortium blockchains are jointly governed by multiple organizations. True. False.

Hyperledger Fabric uses the same consensus mechanism as Bitcoin. True. False.

Binance Smart Chain uses only 21 validators in its consensus. True. False.

EVM compatibility means a blockchain can run Ethereum smart contracts with minimal modification. True. False.

Nick Szabo coined the term "smart contract" in the 1990s. True. False.

Smart contracts can access external APIs directly without oracles. True. False.

Gas in Ethereum prevents infinite loops by limiting computational work. True. False.

EIP-1559 introduced a base fee that is burned and a priority fee for validators. True. False.

The Ethereum Virtual Machine (EVM) executes bytecode deterministically on all nodes. True. False.

A smart contract's code can be modified after deployment without special patterns. True. False.