Ethereum Multiple Choice Questions

In this article, we test our understanding of Ethereum with 60 multiple choice questions.

1. Which year was Blockchain technology created? (a) 2008. (b) 2009. (c) 2010. (d) 2015.

Ans: (a) Explanation: Blockchain technology was introduced in October 2008 as part of a proposal for the Bitcoin system.

2. Which year was Ethereum created? (a) 2017. (b) 2018. (c) 2015. (d) 2020.

Ans: (c) Explanation: The Ethereum blockchain network was conceived in 2013 by Vitalik Buterin and other founders such as Gavin Wood, Charles Hoskinson, Anthony Di Iorio, and Joseph Lubin.

3. Who is NOT a founder of Ethereum? (a) Satoshi Nakamoto (b) Vitalik Buterin (c) Gavin Wood (d) Charles Hoskinson

Ans: (a) Explanation: Satoshi Nakamoto was the creator of the Bitcoin network and NOT Ethereum.

4. How many minutes does it take to mine an Ethereum block? (a) 0 (b) 10 (c) 30 (d) 12

Ans: (a) Explanation: An Ethereum block is mined in less than a minute. Around 12 to 14 seconds a new Ethereum block is mined depending on the network traffic, hashing power, and difficulty, among other factors.

5. Select the consensus algorithm used by Ethereum's PoW mechanism? (a) Solidity (b) Ethash (c) Bellman ford algorithm (d) SHA256 algorithm

Ans: (b) Explanation: Ethash is the proof-of-work mining algorithm that is used by the Ethereum blockchain network.

6. Satoshis is to Bitcoin as __ is to Ethereum? (a) Gwei (b) Wei (c) Ether (d) Bitcoin

Ans: (b) Explanation: Wei is the smallest denomination of Ethereum. On the other hand, Satoshis is the smallest denomination of Bitcoin.

7. In 2022 what is the block reward issued to miners as a result of mining Ethereum blocks.? (a) 2 (b) 3 (c) 6 (d) 10

Ans: (a) Explanation: In 2022, Ethereum miners are rewarded 2 Ether for every block mined.

8. What is the Ghost protocol in Ethereum? (a) A way of processing transactions without broadcasting them. (b) A way of rewarding miners for mining Ethereum blocks. (c) None of the above. (d) A way of paying miners for mining broadcasted transactions.

Ans: (c) Explanation: This protocol reduces forks by rewarding orphan blocks.

9. Which among the following is a difference between Bitcoin and Ethereum? (a) Ethereum uses PoS while Bitcoin uses PoW. (b) Bitcoin scrypt is turing-complete while Ethereum's Solidity is turing-incomplete. (c) Ethereum is more accepted compared to Bitcoin. (d) Ethereum is deflationary while Bitcoin is inflationary.

Ans: (b) Explanation: Scrypt is turing-complete for security purposes while Ethereum's Solidity is turing-incomplete. To handle the issues involving infinite loops, Ethereum uses the concept of gas and gas fees.

10. When was Ethereum's genesis block mined? (a) 2013 (b) 2015 (c) 2018 (d) 2009

Ans: (b) Explanation: The first block to be mined in a blockchain network is referred to as the genesis block. It is the root of trust for the Entire blockchain network.

11. What is gas in the Ethereum context? (a) The computational resources required to perform transactions. (b) The security level of the Ethereum network. (c) The gas produced by Ethereum servers. (d) The required cost to perform a transaction on the network.

Ans: (d) Explanation: Gas is the price for performing a transaction on the Ethereum network. Miners contribute their computational resources to manage the network and in return are incentivized with gas fees paid by the transaction initiator.

12. What are ommer blocks in Ethereum? (a) Unwanted mined Ethereum blocks. (b) Blocks created during the PoW competition that did not get selected. (c) Blocks that have already been mined and added to the blockchain. (d) None of the above.

Ans: (b) Explanation: Ommer blocks are created when two miners mine the next block at the same time. In such a case, a single block will be added to the ledger, the remaining blocks are referred to as ommer blocks.

13. What are ommer rewards blocks in Ethereum? (a) Rewards to miners for creating ommer blocks. (b) Reward to miners for creating Ethereum blocks. (c) Reward to miners for processing transactions from Uncle blocks. (d) Reward to miners for network participation.

Ans: (a) Explanation: In Ethereum when two competing miners mine a block at roughly the same time, a single block is selected and the rest are referred to as ommer blocks. Ommer miners are also incentivized to improve the security of the network.

14. What are uncle blocks in Ethereum? (a) Blocks that are roughly mined at similar times. (b) Valid blocks rejected by the network in Ethereum. (c) Blocks from another blockchain such as Bitcoin. (d) None of the above.

Ans: (b) Explanation: Uncle blocks are valid blocks that have been rejected by the Ethereum network. These blocks are not mined onto the canonical chain.

15. Which statement best describes Ethereum? (a) A Bitcoin clone with programmability. (b) A server company located in the US. (c) A cryptocurrency derived from Bitcoin. (d) A distributed computer with a Native currency.

Ans: (d) Explanation: Ethereum is a distributed computer system with its native currency referred to as Ether. Reading the state of the world computer is free however changing the state costs gas fees since computations need to be performed.

16. What are uncle rewards in Ethereum? (a) Rewards are awarded to miners who create an uncle block included in a side chain. (b) Rewards are awarded to miners who create a valid block included in a valid block added to the chain. (c) Rewards awarded to miners who create an ommer block included in a valid block added to the chain. (d) Rewards are awarded to miners who create an uncle block included in a valid block added to the chain.

Ans: (d) Explanation: Uncle rewards are rewards that are rewarded to miners who create uncle blocks that are included in a valid block that is added to the canonical network.

17. During the conception of Ethereum, how many Ether existed? (a) 21 million (b) 21 billion (c) 71 million (d) 72 million

Ans: (d) Explanation: At launch, 72 million Ether were generated.

18. What is a difference between Ethereum and Bitcoin? (a) Ethereum was crowdfunded, Bitcoin was not. (b) Bitcoin was crowdfunded, Ethereum was not. (c) None of the above. (d) All of the above.

Ans: (a) Explanation: Ethereum is a crowd-funded project while Bitcoin is not.

19. Ethereum is a __ blockchain? (a) Public. (b) Private. (c) Consortium. (d) None of the above.

Ans: (a) Explanation: Ethereum is a public blockchain that is accessible to anyone.

20. What is Ether? (a) A cryptocurrency invented by Satoshi Nakamoto. (b) The fiat version of Ethereum crypto-currency. (c) The lowest denomination of Ethereum native currency. (d) None of the above.

Ans: (d) Explanation: Ether is the native cryptocurrency for the Ethereum blockchain network.

21. When was Ethereum's White paper published? (a) 2015 (b) 2008 (c) 2014 (d) 2009

Ans: (c) Explanation: The Ethereum whitepaper was published in 2014. It proposed Ethereum as a peer-to-peer blockchain network. For more information, this link is helpful.

22. How many transactions per second could Ethereum process in January 2016? (a) 25 (b) 10000 (c) 100 (d) 50

Ans: (a) Explanation: After its release in 2015, Ethereum could process 25 transactions per second by 2016 January. At the writing of this MCQ, Ethereum can process 100,000 transactions per second.

23. How many hexadecimal characters does an Ethereum address have? (a) 30 (b) 20 (c) 40 (d) 60

Ans: (c) Explanation: An Ethereum is composed of 40 hexadecimal characters, unlike Bitcoin addresses which consist of 27 to 35 alphanumeric characters.

24. Which is NOT a type of Ethereum address? (a) Externally Owned Address. (b) Contract Address. (c) Receiving Address. (d) None of the above.

Ans: (c) Explanation: We can have two types of Ethereum addresses. An Externally Owned Address of Contract Address. For differences between the two, this link_ is helpful.

25. Select the fork that will introduce Ethereum 2.0? (a) Metropolis (b) Harmony (c) Serenity (d) Classic

Ans: (c) Explanation: Serenity is meant to make Ethereum more scalable, resilient, secure, and decentralized.

26. What was the total raised for the Ethereum crowd sale? (a) 18 million. (b) 20 million. (c) 16 million (d) 11 million.

Ans: (a) Explanation: Ethereum crowd sale saw USD 18.4 million being raised.

27. What is Ethereum Classic? (a) An Ethereum hard fork. (b) A Bitcoin hard fork. (c) A Bitcoin soft fork. (d) An Etherum soft fork.

Ans: (a) Explanation: A hard fork is a radical change to a network's protocol. This is what happened to Ethereum after the DAO hack.

28. Why do we have Ethereum and Ethereum Classic? (a) As a result of a hack. (b) To scale the Ethereum blockchain. (c) None of the above. (d) All of the above.

Ans: (a) Explanation: The fork came as a result of a DAO hack whereby a hacker managed to withdraw $50 million(1/3 all circulating ETH) from the DAO wallet.

29. Elliptic curve cryptography follows the associative property.? (a) True (b) False (c) None of the above (d) Maybe

Ans: (a) Explanation: Elliptic curve cryptography follows the associative property.”

30. What is the number of round computation steps in the SHA-256 algorithm? (a) 88 (b) 64 (c) 128 (d) 256

Ans: (b) Explanation: There are 64 round computation steps in the SHA-256 algorithm.

31. What is the approximate number of ETH mined every year? (a) 20 million. (b) 11 million. (c) 16 million (d) 18 million

Ans: (d) Explanation: Ether capped its limit to 18 million ETH mined yearly.

32. BIPs are to Bitcoin what ___ are to Ethereum? (a) EIPS. (b) BIPS. (c) None of the above. (d) KIPS.

Ans: (a) Explanation: EIPS are improvement proposals for the Ethereum protocol. EIPs describe standards for Ethereum.

33. Which is NOT an Ethereum testnet? (a) Kovan. (b) Ropsten. (c) Rinkeby. (d) Safaricom.

Ans: (d) Explanation: A test network is a mock of the main network. In this case, Rinkeby, Kovan, Ropsten, and Goerli mock the real Ethereum network protocol. Testnets are used to test decentralized applications during development.

34. What language is used to write Ethereum smart contracts? (a) Python. (b) Rust. (c) Solidity (d) Vyper.

Ans: (c, d) Explanation: Solidity and vyper are the main high-level programming languages used to write smart contracts that execute logic on the Ethereum protocol.

35. Which is NOT an Ethereum client? (a) Geth(Go) (b) OpenEth(Rust) (c) Nethermind(C#, .NET) (d) Bitcoind(C++)

Ans: (d) Explanation: Other Ethereum clients include, Besu written in Java, and Erigon written in the go programming language.

36. Which is NOT a type of an Ethereum client? (a) Full client. (b) Light client. (c) SPV client. (d) Remote client.

Ans: (c) Explanation: Full client/nodes store the entire copy of the blockchain. Light clients store a copy of the entire blockchain, they gate their information from full clients. A remote client does not validate or store any blockchain data. Remote clients are mainly used to implement crypto wallets.

37. Which is NOT an Ethereum wallet type? (a) Public wallet. (b) Software wallet. (c) Paper wallet. (d) Hardware wallet.

Ans: (a) Explanation: We can store Eth in software wallets(desktop, mobile, web), paper wallets, or hardware wallets(usb). The latter is the safest although inconvenient to daily crypto users. Software wallets are the most commonly used wallets. Paper wallets can succumb to wear and tear.

38. What is the name of the Virtual Machine that compiled Solidity/Vyper code into bytecode for execution on the blockchain? (a) JVM (b) EVM (c) GCC (d) G++

Ans: (b) Explanation: The Ethereum Virtual Machine compiles smart contracts written in Solidity of Vyper into byte code that can be executed on the blockchains.

39. Where do decentralized apps store their data? (a) Google servers. (b) Microsoft servers. (c) Amazon servers. (d) A decentralized network of nodes.

Ans: (d) Explanation: Fully decentralized apps store their data on the blockchain which is a network of nodes.

40. In 2021, what was the all-time high price for Ether? (a) 3500 (b) 2200 (c) 4800 (d) 4000

Ans: (c) Explanation: In May 2021, Ether was valued at $4800 per Ether.

41. What was the highest amount paid for an Ethereum transaction? (a) $300000 (b) $200000 (c) $100000 (d) $400000

Ans: (a) Explanation: $300000 is the highest amount in USD pad for a transaction on the Ethereum network.

42. What is Metamask? (a) A browser extension to generate private keys. (b) A browser extension to sign transactions with a private key. (c) A browser extension to operate on the Bitcoin blockchain. (d) None of the above.

Ans: (b) Explanation: Metamask is a browser extension that is used to sign transactions with a private key no matter the blockchain network. It connects to any blockchain via RPC.

43. What is the highest denomination of Ethereum's native cryptocurrency? (a) Ether (b) Gwei (c) Tether (d) Wei

Ans: (a) Explanation: Ether is the highest Ethereum denomination.

44. Select the correct order for Ethereum denominations? (a) Gwei, Wei, Szabo, Finney, Ether (b) Wei, Gwei, Finney, Szabo, Ether (c) Wei, Finney, Szabo, Ether, Tether (d) None of the above

Ans: (d) Explanation: Ethereum's order of denominations is, Wei, Kwei(babbage), Mwei(lovelace), Gwei(shannon), Szabo(microether), Finney(milliether), and Ether.

45. What is a nonce? (a) The sum of all ethers in a contract address. (b) A number of transactions in a block. (c) A number to prevent against replay attacks. (d) A checksum of the hash of the previous block.

Ans: (c) Explanation: A nonce is a number only used once to prevent against replay attacks. If the number is used once, then we expect every transaction to have a different nonce. This number is increased every time we send a transaction from an account.

46. Select the correct statement? (a) An address is 20 bytes long, a public key 64 bytes, and the private key 32 bytes (b) An address is 20 characters long, a public key 32 characters long, and a private key 64 characters long (c) There is no public key, the public key is the address, both are 20 bytes, the private key 32 bytes long (d) None of the above.

Ans: (a) Explanation: An Ethereum address is 20 bytes long. The public key is 64 bytes long, to get the public address, we hash(keccack-256) it and take the last 20 bytes. The private key is 32 bytes long.

47. What is the approximate number of transactions that can be placed in a single Ethereum block? (a) 1250 (b) 25 (c) 380 (d) 420

Ans: (c) Explanation: The largest block size in Ethereum is around 8 million gas and an ETH transaction consumes 21000 gas meaning that we can have approximately 380 transactions in a single block.

48. What hashing algorithm is used in Ethereum? (a) MD5 (b) SHA-1 (c) Keccack-256 (d) None of the above.

Ans: (c) Explanation: Ethereum uses the Keccack-256 hashing algorithm for its hashing needs.

49. What data structure is used to store transactions in a block? (a) Trees (b) Lists (c) Linked lists (d) Graphs

Ans: (a) Explanation: A Merkle tree is a tree data structure that is used to store transactions in an Ethereum block.

50. Which of the statements is FALSE regarding contract accounts? (a) Have a balance. (b) Controlled and owned by blockchain participants. (c) Have a contract associated with them. (d) Have a persistent state.

Ans: (b) Explanation: Contract accounts are NOT controlled by participants rather are associated with smart contracts that live on the Ethereum blockchain.

51. Which is the statement is FALSE regarding EOA Ethereum accounts?? (a) Have an ETH balance. (b) Are owned and controlled by blockchain users. (c) Have contract code associated with them. (d) Can send or receive transactions.

Ans: (c) Explanation: EOA accounts have no contract code associated with them.

52. What does gas fees cater for? (a) Computations in a single block. (b) Storage space in a block. (c) Computations on the network. (d) All the above.

Ans: (d) Explanation: Gas fees are costs associated with all transactions on the blockchain.

53. What is the result of transacting with insufficient gas fees? (a) Pending transactions. (b) Slower transactions. (c) Transaction failure. (d) None of the above.

Ans: (a) Explanation: If gas fees are insufficient the transaction will sit idle on the network and won't be processed.

54. Which of the statements is TRUE? (a) Gas is a fee paid to miners for mining blocks. (b) Gas is the cost of computational work on the blockchain. (c) Gas is NOT mandatory when sending ETH transactions. (d) Gas fees are based on the size of a transaction.

Ans: (b) Explanation: Gas is the cost for computational work.

55. Why is hashing used in Ethereum? (a) To compare data. (b) To evaluate the validity of data (c) To produce a transaction signature for all block transactions. (d) All of the above.

Ans: (d) Explanation: Hashing and public-key cryptography are what make blockchains such as Ethereum secure.

56. What is a state machine.? (a) All the below. (b) Computers with memory. (c) Computers with a global state. (d) Computers that are never offline.

Ans: (a) Explanation: Ethereum state machine is a machine with a large data structure that holds not only all accounts and balances, but a machine state, which can change from block to block according to a pre-defined set of rules, and which can execute arbitrary machine code.

57. What are Dapps? (a) Apps that run on central servers. (b) Apps that run on a blockchain. (c) Apps that run on a decentralized blockchain. (d) None of the above.

Ans: (c) Explanation: Dapps are applications that run on a decentralized blockchain such as Ethereum.

58. Which is a use case of smart contracts? (a) Supply chains. (b) Gambling. (c) Decentralized finance. (d) All the above.

Ans: (d) Explanation: Smart contracts have a wide variety of use cases. They can be used in decentralized finance(trading, borrowing, lending), and insurance.

59. What is the approximate size of an Ethereum block in MBs? (a) 4 (b) 8 (c) 16 (d) 32

Ans: (a) Explanation: An Ethereum block is around 80KBs which is about 4MBs.

60. Which is a step involved in smart contract development? (a) Reconfirm is your business needs a smart contract. (b) Understand the limitations of a smart contract. (c) Hiring a smart contract developer. (d) All the above.

Ans: (d) Explanation: We also need to plan out the development process and test the smart contract thoroughly before deploying it to the blockchain.