CBDE Exam Dumps : BTA Certified Blockchain Developer - Ethereum

would be better, because it can reduce the amount of energy needed for mining.

would be worse, because it would increase the amount of energy needed for mining.

with private state variables. This way nobody else other than the smart contract itself can see the information

with external contracts holding those values. This way we can make sure that the information flow is following a clear logic and nobody else can access this information.

You can't hide anything on the blockchain, because the information is public, just the call is private which means only other smart contracts would be limited in accessing that information.

.send returns a Boolean and .transfer throws an exception on error. Both just forward the gasstipend of 2300 gas and are considered safe against re-entrancy.

.send throws an exception and .transfer returns a Boolean on error. Both just forward the gasstipend of 2300 gas and considered safe against re-entrancy

.send returns a Boolean and .transfer throws an exception on error. .send is considered dangerous, because it sends all gas along, while .transfer only sends the gas stipend of 2300 gas along

.send and .transfer are both considered low-level functions which are dangerous, because they send all gas along. It's better to use address.call.value()() to control the gas-amount.