With reference to “Blockchain Technology”, consider the following statements: 1) It is a public ledger that everyone can inspect, but which no single user controls. 2) The structure and design of blockchain is such that all the data in it are about cryptocurrency only. 3) Applications that depend on basic features of blockchain can be developed without anybody’s permission. Which of the statements given above is/are correct?

The correct answer is D (1 and 3 only). Blockchain is a distributed, append-only ledger replicated across many nodes, so anyone on the network can inspect it, but no single participant controls it. That is statement 1, and it is correct.

• Statement 1 is correct. Consensus among nodes, not a central authority, validates each block. This is the core property that makes it a public ledger without a single owner.
• Statement 2 is wrong. Cryptocurrency was the first application (Bitcoin, 2008–09), but blockchain is a general data structure. It is used for supply-chain tracking, land records, digital identity, healthcare records and trade finance. Confusing the platform with its first application is a common error.
• Statement 3 is correct. Public (permissionless) blockchains like Ethereum let any developer build decentralised applications (dApps) on the base layer without seeking approval from a gatekeeper. Permissioned blockchains work differently, and the question tests whether you know the distinction.

Connection to syllabus: this falls under Science and Technology (emerging technologies, IT). For Mains GS-III, link it to digital governance, e-governance security and the regulatory challenges of crypto assets in India, where the RBI has taken a cautious stance.

Trap: Students reject statement 3 because they associate blockchain only with crypto trading. Separate the technology from its applications, and separate public from permissioned blockchains.