Blockchain Developer Token Standards and NFTs 2 — Questions and Answers
Question 1: Which ERC standard introduced a single contract capable of managing multiple token types, both fungible and non-fungible?
- ERC-721
- ERC-1155 (Correct answer)
- ERC-20
- ERC-777
Correct answer: ERC-1155
ERC-1155 is the multi-token standard allowing one contract to handle fungible, non-fungible, and semi-fungible tokens.
Question 2: In ERC-721, what function returns the owner of a specific token ID?
- balanceOf
- ownerOf (Correct answer)
- tokenURI
- approve
Correct answer: ownerOf
ownerOf(tokenId) returns the address that owns the given NFT.
Question 3: What does the ERC-721 metadata function tokenURI typically return?
- The token's price
- A URI pointing to a JSON metadata file (Correct answer)
- The owner's address
- The contract's bytecode
Correct answer: A URI pointing to a JSON metadata file
tokenURI returns a URI that resolves to JSON metadata describing the asset (name, image, attributes).
Question 4: Why is ERC-1155 considered more gas-efficient than deploying many ERC-721 contracts?
- It uses no storage
- It supports batch transfers of multiple token types in one call (Correct answer)
- It removes the need for a blockchain
- It eliminates approvals entirely
Correct answer: It supports batch transfers of multiple token types in one call
ERC-1155's safeBatchTransferFrom moves multiple token IDs and amounts in a single transaction, reducing gas.
Question 5: Which interface detection standard do ERC-721 contracts implement so others can query supported interfaces?
- ERC-165 (Correct answer)
- ERC-20
- ERC-1820
- ERC-4626
Correct answer: ERC-165
ERC-165 defines supportsInterface, used to advertise which interfaces (like ERC-721) a contract implements.
Question 6: In ERC-1155, what does the balanceOf function require as arguments?
- Only an address
- An address and a token ID (Correct answer)
- Only a token ID
- A URI
Correct answer: An address and a token ID
Because one contract holds many token types, balanceOf(account, id) needs both the holder and the specific id.
Question 7: What is a key risk of storing NFT metadata at a centralized HTTP URL rather than on IPFS?
- Higher gas fees
- The metadata/image can change or disappear, breaking the NFT (Correct answer)
- It prevents transfers
- It increases token supply
Correct answer: The metadata/image can change or disappear, breaking the NFT
Centralized URLs are mutable and can go offline, so the referenced image or data may change or vanish.
Blockchain Developer Token Standards and NFTs 2
Which ERC standard introduced a single contract capable of managing multiple token types, both fungible and non-fungible?