CBDE Blockchain BTA Certified Blockchain Developer - Ethereum Free Practice Exam Questions (2025 Updated)

both are the same, just implemented in a different language.

with Go-Ethereum you get a real blockchain node where you can create your own local private network, connect to Test-Networks or the Main-Net, while with Ganache you get an in-memory blockchain simulation.

with Ganache you get a real blockchain node where you can connect to the Test-Networks Rinkeby and Ropsten.

Integer, Boolean, Struct, Mapping and Enum.

Integer, Boolean, Enum and Addresses.

Integer, Boolean, Structs and Fixed Point Numbers.

working with either // or ///

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

not possible, all comments must be multi-line.

are a great way to circumvent gas requirements, because a loop will only consume gas once.

are dangerous when used with data structures that grow, such as arrays or mapping, because it is hard to estimate the gas requirements.

should be avoided where possible, because of unknown side-effects on the gas requirements.

for Java, JavaScript, and C++

for JavaScript using Web3.js

for Solidity and JavaScript

for any language, as long as it adheres to the open Testing-Interface from Truffle

the timestamp is based on the time zone of the miner, that is why it changes the difficulty continuously to reflect network latency.

the timestamp can't be influenced by a miner and is generally considered safe to be used for randomness on the blockchain.

the timestamp can be influenced by a miner to a certain degree but it's always independent from the time-zone.

all public state variables and properties, public and internal functions and modifiers.

all public and private state variables, public, internal and external functions, but not modifiers

all public state variables and properties, public functions and modifiers, but not internal, external or private ones.

Address.call() is used for calling other contracts using the scope of the called contract in terms of storage variables. Address.delegatecall() is used for libraries, which uses the storage variables of the contract who called. Libraries are a great way to re-use already existing code and delegatecall can make sure that no storage is used from the library, instead it looks like the code is directly copied into the calling contract.

Address.delegatecall() is used for calling other contracts using the scope of the called contract in terms of storage variables. Address.call() is used for libraries, which uses the storage variables of the contract who called. Libraries are a great way to re-use already existing code and call() can make sure that no storage is used from the library, instead it looks like the code is directly copied into the calling contract.

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

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

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

the amount of gas your contract deployment and transactions, against your contract, will need. This way you can essentially lower the gas costs over traditional web3.js dApps.

different Networks to deploy your contracts to. This way you can easily deploy to a local blockchain, the main-net or the Ropsten/Rinkeby Test-Net with only one parameter.

you can manage your secret API keys to the Ethereum Network. This way you can get access to several different Ethereum nodes at the same time without the need to switch your keyfiles.

2, because the decimal is truncated.

3, because it's always rounded.

2.5, because it's automatically converted into a float.

using relative and absolute paths, where the "." And the ".." depict that it's a relative path.

only via GitHub using the Repository and Username.

using the special requirefile(...) statement, which looks in a specific library path to import files.

all gas is consumed.

all remaining gas is returned.

can help to engage the community in testing your smart contracts and therefore help to find bugs early.

might be a burden as it is an administrative overhead mainly.

is completely useless. Who wants to test beta-ware software? It’s better to start with the bug-bounty program after the contract is released on the main-net.

to deploy to the main-network as quickly as possible.

to use in-memory blockchain simulations, because mining works instantaneously.

to use a private network at all times, because this is the closest you get to the real network.

all gas is consumed

all remaining gas is returned.

it always produces the same output given the same input.

it uses equally distributed data to produce the output given a long input.

it shouldn't be possible to re-generate the input given the output.

It helps you to find bugs, regression bugs and sometimes also helps you to understand your code from different angles.

It is a great way to spend time on something that you get paid for. But ultimately it will just slow down the development process.

it’s good to use a push over a pull method.

it’s good to use a push and a pull method to ensure that participants can get their money no matter the contract state. In addition to and pushing it should contain a withdraw method.

it's good to use only pull and no push method.