Unit 1: Blockchain concepts - Practice Quiz

1 In a blockchain-based escrow, what typically holds the funds until conditions are met?

2 What is the main purpose of an escrow arrangement?

3 A key benefit of using blockchain for escrow is that it reduces the need for a:

4 In a smart contract escrow, funds are released when:

5 Which layer of the blockchain stack typically contains the peer-to-peer communication protocols?

6 In the blockchain stack, where do decentralized applications (dApps) usually reside?

7 Which layer is responsible for agreeing on the valid state of the ledger across nodes?

8 The data layer of the blockchain stack is mainly concerned with:

9 A defining feature of Web 2.0 compared to the decentralized web is that Web 2.0 is largely:

10 The decentralized web (Web 3.0) aims to give users more:

11 Which technology is a core foundation of the decentralized web?

12 In Web 2.0, user data is typically stored on:

13 Which domain uses blockchain to track goods from origin to consumer?

14 In healthcare, blockchain is often used to securely manage:

15 Which financial application is a common domain-specific use of blockchain?

16 Decentralized Finance (DeFi) belongs to which domain of blockchain applications?

17 Which of the following is a key benefit of blockchain?

18 A common challenge faced by many blockchain networks is:

19 Which property makes blockchain records very hard to alter once added?

20 High energy consumption is most associated with which blockchain consensus mechanism?

21 In a blockchain-based escrow using a smart contract, a buyer deposits funds that are released only after both parties confirm delivery. What role does the smart contract primarily replace compared to traditional escrow?

22 A smart-contract escrow is designed to release payment when a condition is met. If the condition depends on real-world delivery confirmation, what external component is typically required?

23 In a decentralized escrow, a dispute arises and a neutral arbiter must decide the outcome. Which design pattern best supports this requirement?

24 In the layered blockchain stack, which layer is primarily responsible for propagating transactions and blocks between nodes?

25 A developer builds a dApp with a user interface, smart contracts, and uses a node provider to read chain data. In which layer of the blockchain stack do the smart contracts primarily execute?

26 Which component of the blockchain stack is responsible for ensuring all nodes agree on a single valid version of the ledger?

27 In the blockchain stack, decentralized storage solutions like IPFS are often used alongside the chain. What problem do they primarily address?

28 A key distinction between Web 2.0 and the decentralized web (Web 3.0) is the handling of user data. Which statement best captures this difference?

29 In Web 2.0, user authentication typically relies on a username/password stored by a provider. What is the equivalent mechanism in the decentralized web?

30 Which characteristic is most associated with the transition from Web 2.0 to the decentralized web?

31 A social media dApp lets users keep their content even if the front-end provider shuts down. Which decentralized web property enables this?

32 In supply chain management, blockchain is often used to track products from origin to consumer. Which property makes it suitable for this use case?

33 A healthcare provider wants patients to control who accesses their medical records. Which blockchain feature most directly supports this requirement?

34 In the finance domain, which application is a direct example of a domain-specific blockchain use case?

35 An electoral commission considers blockchain-based voting. Which benefit is the strongest motivation for this domain-specific application?

36 The "scalability trilemma" states that a blockchain struggles to simultaneously maximize three properties. Which set correctly lists them?

37 A company adopts a public blockchain but worries about transaction confidentiality. Which challenge does this concern highlight?

38 Which of the following is primarily a benefit rather than a challenge of blockchain technology?

39 A developer notes that once a transaction is confirmed and buried under many blocks, reversing it is practically infeasible. This describes which blockchain property?

40 An enterprise finds that two different blockchains cannot easily exchange assets or data. Which challenge does this illustrate?

41 In a smart-contract escrow with buyer, seller, and a 2-of-3 arbitrator-mediated multisig, a dispute arises and the arbitrator colludes with the seller to release funds for undelivered goods. Which design property is fundamentally violated, and what is the correct architectural fix?

42 A decentralized escrow locks funds until a shipment oracle confirms delivery. The oracle feed can be delayed by up to 48 hours. An attacker front-runs the release transaction after seeing the oracle update in the mempool. Which combination of safeguards best mitigates this specific threat?

43 Consider an escrow contract that refunds the buyer if the seller does not act within blocks. The chain suffers a reorg of depth where spans the timeout boundary. What is the core risk this creates?

44 In the canonical blockchain stack, a dApp needs sub-second UX for reads but trust-minimized settlement for value transfer. Which layering decision correctly separates these concerns?

45 A rollup publishes compressed transaction data to a base layer and posts validity proofs. Which layer of the blockchain stack is being leveraged for data availability, and why is it distinct from execution?

46 Which statement most accurately characterizes the relationship between the protocol/consensus layer and the application layer in terms of upgrade coupling?

47 A wallet signs a transaction locally, broadcasts it, and later queries balance via an RPC node it does not control. What is the trust assumption introduced strictly by the RPC query step?

48 A team migrates a Web2.0 app to a decentralized architecture but keeps user media on a single cloud bucket while storing hashes on-chain. Which claim about this hybrid is correct?

49 In the shift from Web2.0 to the decentralized web, which trade-off most directly explains why fully on-chain social applications remain rare?

50 A decentralized web app uses content-addressed storage (CID = hash of content). A developer wants to update a user's profile while keeping a stable reference. What mechanism resolves the inherent tension between immutability and mutability?

51 Which outcome best captures how data ownership differs structurally between Web2.0 and the decentralized web?

52 A supply-chain blockchain records each shipment handoff. A critic argues it cannot prevent recording that a counterfeit item is 'authentic' at origin. Which concept names this limitation precisely?

53 For a healthcare records use case requiring GDPR-style erasure, why is a naive public, immutable on-chain store problematic, and what is the standard mitigation?

54 A consortium of competing banks wants shared settlement with confidential balances but auditable rules. Which blockchain design is most appropriate?

55 A voting dApp claims end-to-end verifiability on a public chain. Which pair of requirements is in direct tension, demanding a specialized cryptographic approach?

56 An architect claims migrating an internal, single-organization approval workflow to a blockchain will add value. Under which condition is this claim least justified?

57 Regarding the scalability trilemma, a chain increases block size to raise throughput. Which second-order challenge most directly results?

58 A system markets 'immutability' as a pure benefit. Which scenario best demonstrates immutability acting as a challenge rather than a feature?

59 Two parties argue about finality. One cites a probabilistic-finality chain, the other a deterministic/BFT-finality chain. Which statement correctly contrasts the settlement-risk implication?

60 A privacy-focused design publishes transaction amounts on a public chain but hashes the counterparties. Why does this often fail to provide real privacy?