Install GCC 7.20 on Ubuntu 22.04

I saw this question several years ago, but it is worth asking.

I have to do a coding test on "GCC 7.2.0 (with -std=c++17)" I have in my Ubuntu: "gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)"

They say, "Your solution will be compiled with GCC 7.2.0 (with -std=c++17), and you will have the chance to fix any compilation errors before submission."

Now I have two questions:

1. Can I install GCC 7.2.0 on my Ubuntu without creating a VM?
2. Can I code in my environment and send it? The compiler should have backward compatibility because it should be just an algorithm for an online test, and they are saying: "You may use the standard libraries for the task. It is not permitted to use other libraries. However, you will not need them anyway."?

Thank you!