I want to know whether the CPU executes operations instructions during runtime in the same sequence obeying rules used in precedence to evaluate a value of an expression or not.
There are a few things to clarify. A C source code is "translated" into machine code by the compiler. There is never a 1 to 1 relationship between C code/instructions and machine code/instructions.
When compiling code the only thing that matters is the as if rule. As long as the observable behavior of the program is preserved, the compiler can generate instructions in any order.
Furthermore, on the hardware level, the CPU has its own mechanism for detecting instruction dependencies and can itself execute instructions out of order or in parallel (e.g. a single core has more than 1 ALU and FPU).
So, for a correct C program, the observable behavior of the program will be preserved. Instructions can be reordered, parts of code completely skipped and even algorithms completely changed underneath (e.g. modern compilers can transform recursive functions into non-recursive functions with loop constructs). But the observable behavior of the program will not change.