Bitcoin Blockchain Architecture BBLC Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A Bitcoin exchange is planning to support a proposed soft fork that introduces a new transaction type. The exchange's CTO is concerned about the risk of accepting transactions that are invalid under the new rules. What is the primary risk to the exchange if it does not upgrade its nodes?

   • AThe exchange's nodes will be unable to sync with the network because soft forks require a hard fork to activate.
   • BThe exchange's nodes will be forked onto a separate chain, and the exchange will lose all its bitcoins.
   • CThe exchange will be forced to upgrade immediately or its nodes will be shut down by the network.
   • DThe exchange may accept transactions that are valid under old rules but invalid under the new soft fork rules, leading to financial loss.
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   In the Bitcoin UTXO model, what does an unspent transaction output (UTXO) represent?

   • AA cryptographic hash of a block header
   • BThe total supply of bitcoin that will ever be mined
   • CA record of a transaction that has been reversed
   • DA specific amount of bitcoin that is available to be used as an input in a future transaction
   Reveal Solution Discussion Select an answer first
4. 18foundation · easy

   What is the 'longest chain rule' in Bitcoin?

   • ANodes always consider the chain with the most cumulative proof-of-work as the valid one
   • BNodes always choose the chain that was created first
   • CNodes always choose the chain with the most transactions
   • DNodes always choose the chain with the highest transaction fees
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   A retail business accepts Bitcoin payments. A customer pays 0.5 BTC for a purchase, but the customer's wallet had previously received two separate deposits: 0.3 BTC and 0.4 BTC. The customer's wallet constructs a transaction spending both deposits as inputs. Which statement accurately describes how the Bitcoin network determines the customer's available balance and processes this payment?

   • AThe network automatically selects the largest deposit (0.4 BTC) as the input, sends 0.5 BTC to the merchant, and ignores the smaller deposit because it is insufficient.
   • BThe network checks the customer's wallet balance as a single number stored on the blockchain; the wallet subtracts 0.5 BTC from that balance and records the payment as a new balance entry.
   • CThe network sums all unspent transaction outputs (UTXOs) controlled by the customer's private key; the transaction consumes both 0.3 BTC and 0.4 BTC as inputs and creates one 0.5 BTC output to the merchant and one 0.2 BTC change output back to the customer.
   • DThe network requires the customer to first combine the two deposits into one UTXO in a separate transaction, then send the combined 0.7 BTC to the merchant in a second transaction.
   Reveal Solution Discussion Select an answer first
6. 20foundation · easy

   What is the primary role of a full node in the Bitcoin network?

   • ATo provide a user-friendly interface for sending transactions
   • BTo validate transactions and blocks according to the network's consensus rules
   • CTo store users' private keys securely
   • DTo create new bitcoins through mining
   Reveal Solution Discussion Select an answer first