Crypto Jobs Blockchain Fundamentals 3 — Questions and Answers
Question 1: What is a smart contract?
- A legal document stored offline
- Self-executing code on a blockchain that runs when conditions are met (Correct answer)
- A type of hardware wallet
- A mining agreement between pools
Correct answer: Self-executing code on a blockchain that runs when conditions are met
Smart contracts are programs deployed on-chain that automatically execute predefined logic when triggered.
Question 2: What is 'gas' on a network like Ethereum?
- The fee paid to compensate for computational work (Correct answer)
- The native coin's nickname
- A type of consensus algorithm
- Storage allocated to a wallet
Correct answer: The fee paid to compensate for computational work
Gas measures and prices the computational effort required to execute operations, paid to validators.
Question 3: What is the difference between a public and a private blockchain?
- Public chains are slower by law
- Public chains allow anyone to participate while private chains restrict access (Correct answer)
- Private chains have no ledger
- Public chains cannot use encryption
Correct answer: Public chains allow anyone to participate while private chains restrict access
Public blockchains are permissionless and open, whereas private (permissioned) chains limit who can read or validate.
Question 4: What is a cryptographic hash function expected to do?
- Reverse easily back to the input
- Produce a fixed-length, deterministic output that is hard to reverse (Correct answer)
- Change output randomly each run for the same input
- Encrypt data with a shared password
Correct answer: Produce a fixed-length, deterministic output that is hard to reverse
A good hash function is deterministic, one-way, and collision-resistant, producing fixed-length digests.
Question 5: What problem does the 'double-spending' issue describe?
- Paying two fees for one transaction
- Spending the same digital coin more than once (Correct answer)
- Buying a coin twice on an exchange
- Two miners finding a block at once
Correct answer: Spending the same digital coin more than once
Double-spending is the risk of using the same units twice, which consensus and confirmations prevent.
Question 6: What is a fork in a blockchain?
- A divergence in the chain's history or protocol rules (Correct answer)
- A tool for mining
- A type of wallet backup
- A failed transaction
Correct answer: A divergence in the chain's history or protocol rules
A fork occurs when the chain splits, either temporarily due to competing blocks or permanently from a rule change.
Question 7: What is the genesis block?
- The most recent block
- The very first block of a blockchain (Correct answer)
- A block with no transactions
- The block that triggers a halving
Correct answer: The very first block of a blockchain
The genesis block is the first block, hardcoded into the protocol with no predecessor.
