Blockchain 101 Certification Blockchain 101 Certification Smart Contracts & DApps 1 — Questions and Answers
Question 1: What is a smart contract?
- A legal PDF stored on a blockchain
- Self-executing code stored on a blockchain that runs when predefined conditions are met (Correct answer)
- An encrypted email agreement
- A multi-signature wallet
Correct answer: Self-executing code stored on a blockchain that runs when predefined conditions are met
Smart contracts are programs deployed on a blockchain that automatically execute agreed-upon logic when specific conditions are satisfied without intermediaries.
Question 2: Which programming language is primarily used to write Ethereum smart contracts?
- JavaScript
- Python
- Solidity (Correct answer)
- Rust
Correct answer: Solidity
Solidity is the most widely used statically-typed, contract-oriented programming language for writing Ethereum smart contracts.
Question 3: What is the Ethereum Virtual Machine (EVM)?
- A cloud server hosting Ethereum nodes
- A sandboxed runtime that executes smart contract bytecode on every Ethereum node (Correct answer)
- A hardware wallet for Ether
- An off-chain computation engine
Correct answer: A sandboxed runtime that executes smart contract bytecode on every Ethereum node
The EVM is a deterministic stack-based virtual machine that executes smart contract bytecode consistently across all Ethereum nodes.
Question 4: What is 'gas' in the context of Ethereum smart contracts?
- A native token separate from Ether
- A measure of computational effort required to execute operations, paid in Ether (Correct answer)
- A smart contract language feature
- A consensus reward mechanism
Correct answer: A measure of computational effort required to execute operations, paid in Ether
Gas quantifies the computation cost of each EVM operation, and users pay gas fees in Ether to compensate validators for executing their transactions.
Question 5: What is a DApp (Decentralized Application)?
- An app with no user interface
- An application whose backend logic runs on a decentralized blockchain network (Correct answer)
- A mobile app that mines cryptocurrency
- A database distributed across servers
Correct answer: An application whose backend logic runs on a decentralized blockchain network
A DApp combines a user-facing frontend with smart contract backend logic on a blockchain, removing reliance on centralized servers.
Question 6: What is an ABI (Application Binary Interface) in Ethereum development?
- A wallet encryption standard
- A JSON specification describing how to interact with a deployed smart contract (Correct answer)
- A block serialization format
- An identity protocol
Correct answer: A JSON specification describing how to interact with a deployed smart contract
The ABI defines the contract's functions, parameters, and return types so external applications know how to encode calls to the contract.
Blockchain 101 Certification Blockchain 101 Certification Smart Contracts & DApps 1
What is a smart contract?