11.
What is the purpose of the 'std::condition_variable' class in C++ multi-threading?

12.
Which of the following is true about thread safety in C++ multi-threading?

13.
What is the purpose of the 'std::atomic' class in C++ multi-threading?

15.
What is the purpose of the 'std::async' function in C++ multi-threading?

17.
What is the purpose of the 'std::lock_guard' class in C++ multi-threading?

18.
What is the purpose of the 'std::unique_lock' class in C++ multi-threading?

19.
What is the purpose of the 'std::condition_variable_any' class in C++ multi-threading?

20.
What is the purpose of the 'std::packaged_task' class in C++ multi-threading?