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Science and Technology question from UPSC CSE-Prelims, 2026

Which of the following statements regarding the features of blockchain technology are correct?

1. Records stored in the database may be made visible to relevant stakeholders without risk of alteration.
2. Copies of the entire database are stored on multiple computers on a network, syncing within seconds.
3. Consortium blockchain is a blend of public and private blockchains allowing selective data access.
4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.

Last updated Jun 9, 2026
Correct Answer: Option C — 1, 2 and 4
Detailed Analysis of the Statements:
Statement 1 is correct: Blockchain relies on a shared ledger system where records are visible to authorized or relevant stakeholders (depending on permission levels), providing complete transparency while cryptographic security prevents unauthorized alteration.

Statement 2 is correct: A core feature of blockchain is its distributed ledger architecture. Copies of the entire database are stored across multiple nodes (computers) on a network, and consensus protocols ensure they sync almost instantly when a new block is added.

Statement 3 is technically inaccurate in a strict context: While a consortium blockchain restricts access to a specific group of organizations (making it a "federated" or semi-private network), it is not a blend of public and private blockchains. The correct term for a blend of public and private features that allows selective data access to the public while keeping some data private is a Hybrid Blockchain.

Statement 4 is correct: Cryptographic hashing and mathematical consensus algorithms (like Proof of Work or Proof of Stake) ensure immutability. Once data is verified and written into a block, it is practically impossible to alter or delete without changing every subsequent block, which requires controlling more than 51% of the network's computing power.
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
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UPSC CSE 2026 Prelims

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Exam UPSC CSE
Stage Prelims
Year 2026
Subject Science and Technology
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