Online Access Free CBDE Exam Questions

Checking the balance of an address inside a loop of a smart contract constantly:

• A.doesn't cost any gas.
• B.cost gas every time we check the balance.

If a User calls contract A and that calls Contract B, then msg.sender in Contract B will contain the address of:

• A.contract A.
• B.the User.

Truffle:

• A.is a framework that helps developers with Testing, Deployment and Management of Smart Contracts and Distributed Applications.
• B.is a library that helps developers to connect to Ethereum nodes, because it abstracts the JSONRPC interface.
• C.is a framework for Java, similar to Web3.js for JavaScript. It's a great way to develop distributed Java enterprise applications.

Address.send() and address.transfer() are considered:

• A.dangerous because they send all gas along, it's better to use address.call.value()().
• B.safe against reentrancy because of the small gas stipend of 2300 gas.

Gas costs accrue on sending a transaction:

• A.only interacting with an already deployed smart contract.
• B.only with a new smart contract deployment.
• C.no matter the content.