C/C++ .. such language doesn't exist [migrated]

I came across several questions in SOO where lot of them make use of the term C/C++ which is (in my opinion) widely accepted in the industry (at least in the last two decades). In general the SOO users ask the person who is asking the question to choose a language: C or C++. Why?

I understand that both of them are different languages but when I was learning C++ I was always told that C is a subset of C++ or C++ is C with classes. And that was quiet true until the appearance of C++x0, C++11 (or the modern C++ 11/14/17 in general). In fact (specially when working on embedded systems) it's very likely to find code written in C++ but with a lot of parts written entirely in pure C language. Here I have several questions:

1. Should I stop using the term C/C++?
2. If the answer to #1 is yes, how would I call a program that use a mix of C and C++?
3. Given that both of them are 'different' languages is it likely that at some point C++ compilers stop supporting code written in the C language (since modern c++ is diverging from the C mentality for basic stuff like pointers, dynamic memory handling, etc)
4. Is there right now any collaboration between the people who makes the standards of C/C++ to keep the compatibility
5. If #4 is yes, such collaboration could end up in the near future with the appearance of the modern c++ (11/14/17)

I know that there already similar questions, but I'm sure that a lot of people share these doubts so I'm very interested to get good answers specially for the points that have to do with the C++ tendency in the near future.

Thanks in advance,