The chrome browser was not responsive and I tried to kill it, but instead of disappearing the process had
<defunct> at its right, and didn't got killed:
<defunct> for a process and why it doesn't get killed?
From your output we see a "defunct", which means the process has either completed its task or has been corrupted or killed, but its child processes are still running or these parent process is monitoring its child process. To kill this kind of process kill -9 PID don't work, you can try to kill with this command but it will show this again and again.
Determine which is the parent process of this defunct process and kill it. To know this run the command:
ps -ef | grep defunct
Then kill -9 637 27872 then verify the defunct process is gone by ps -ef | grep defunct.