Question 1

When considering smart contracts and the blockchain it's good

Options :

A : to move all existing logic to the blockchain, so everything runs on the same system. This way it might be more complex, but easier to maintain

B : to move only those parts to the blockchain that really need the blockchain. This way smart contracts can be easier to read, easier to test and are not so complex

C : to move those parts to the blockchain that deal with Ether transfers. All other parts can remain in traditional database systems. This way only the value-transfer is on the blockchain.

Answer: B

Question 2

Multi-Line Comments in Solidity are:

Options :

A : working with either // or ///

B : working with /* comment */ or /** @.. natspec style */

C : not possible, all comments must be single-line

Answer: B

Question 3

To communicate with an Ethereum node via [removed]

Options :

A : the library you use must make use of the JSON-RPC Interface of an Ethereum Node

B : must Implement the Ethereum Protocol to connect to other Ethereum Nodes.

C : must use Web3.js, which is closed source to communicate to other Ethereum Nodes.

Answer: A

Question 4

Unit-Testing on a local chain is important, because it helps you:

Options :

A : to run tests quickly and especially for free, compared to continuous deployment on the MainNetwork. This way you save a lot of fees, time and costs

B : to run tests in an environment where logging is activated. On the Main-Net you have no access to transaction logs and this is ultimately the information you need to debug your contracts

C : to avoid regression bugs with contracts that are updated constantly on the main-net. Once you update a contract on the main-net, the address stays the same, but the code changes and this can have disastrous side-effects.

Answer: A

Question 5

When using assert to check invariants and it evaluates to false:

Options :

A : all gas is consumed.

B : all remaining gas is returned

Answer: A

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