But that's not what's being asked by OP. Their question is rather simple, and software engineer should be able to answer it on autopilot, without even engaging her brain. As a hiring manager I would end the interview right there and then after the failure to answer something like this.
As an interviewee, I would roll my eyes at the ignorance of the interviewer.
This is the sort of question that reveals the ignorance of the person asking it. The correct answer is "yes". What is 'modern'? There are very modern embedded CPUs that operate in the low MHz range. How much power is being provided? A 'modern' CPU can be underclocked to ridiculous levels for power savings. What's an operation? Are we talking MOV AX, 1 or are we talking hashing a string?
It's the kind of question a dumb person asks thinking they're being quite clever.
Closely enough related to number of basic operations though I'd say. I'll agree with you if it really just is a multiple choice question without context, but the initial poster did not present it that way, but said that explanation/discussion matters. And then your objections are a good starting point for that.
The worst thing you realistically can do to stall your CPU is miss cache every time you read data from RAM. If you do this for every instruction (which would be quite a feat in itself), you divide your instruction throughput by about 200. But even then, and even on the shittiest modern CPU you'll be retiring millions of instructions per second.
