Which is faster among c and c++?...... which is the fastest object oriented language among java,python,c++ and kotlin?

Answer 1

The speed difference between c and c++ is very slim, but compared to other languages you mentioned c++ is the fastest by far

Answer 2

c is fastest closest language to machine code

Answer 3

Backwards compatibility is one of the guarantees of C++ and since it is being constantly developed I believe the C++ compilers and standards are always better. (Exceptions are embedded systems where c++ is not an option)