Free Blockchain CBDE Practice Exam Questions and Answers 2026

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Total 102 Questions | Updated On: Apr 01, 2026

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Question 1

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

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 2

The Fallback function:

A : cannot receive Ether, not even by adding the payable modifier

B : can contain as much logic as you want, but it’s better to keep it short and not exceed the gas stipend of 2300 gas

C : can be used to avoid receiving ether

Answer: B

Question 3

Smart Contracts can be written in:

A : Java, C++, Solidity and JavaScript, because the Ethereum Blockchain is completely language agnostic and cross compilers exist for every major language

B : Solidity, Viper, LLL and Serpent, because those are high level languages that are compiled down to bytecode.

C : Solidity and JavaScript, because those are the official first implementations for Distributed applications and the Blockchain supports those languages fully.

Answer: B

Question 4

To communicate with an Ethereum node via [removed]

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 5

When defining a new datatype:

A : its best to use a contract with public storage variables, so it can be used like a class

B : it-s best to use a struct, which is cheaper than deploying a new contract

C : it-s not possible to generate new datatypes in Solidity

Answer: B

Page: 1 / 21

Total 102 Questions | Updated On: Apr 01, 2026

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