docker-exec failed: "cd": executable file not found in $PATH

I used this command:
docker exec compassionate_mclean cd /root/python
The error returned is

docker-exec: failed to exec: exec: "cd": executable file not found in $PATH

Kindly help me out

cd is a built-in shell command, you can't set it as the command to run. You have to use:

docker exec -i compassionate_mclean bash -c "cd /root/python && python myscript.py"

If you want to see the output make sure to add the -i flag as shown above. In this case however, you can simply run python as your entrypoint:

docker exec -i compassionate_mclean python /root/python/myscript.py

You can't do that, you can do either docker exec -it my_container /bin/bash and then issue several commands with this interactive sessions, or docker exec -d my_container touch myfile if you just want to create a file, see the examples at https://docs.docker.com/reference/commandline/cli/#examples_3