A question about thesis corrections. The actual topic is somewhat abstract and arcane, so rather than require everyone to start by reading a bunch of acronym definitions, I paraphrase to a more concrete domain:

So: viva done, minor corrections required, so far so good! A lot of the corrections are straightforward ones regarding presentation and suchlike, but there are a few that I'm trying to figure out exactly how to address.

My thesis is about, say, a way to use unobtainium without having to dissolve it first. A comparison with the existing state of the art is expected, so I say things like 'and dissolving unobtainium in sulfuric acid takes a week' (which helps motivate my work; it's useful to be able to skip this long process).

And an examiner writes 'In my experience, hydrochloric acid is more effective at dissolving a lot of at least somewhat similar things. Why not use HCl instead?'

Well, okay. It's a fair comment, that deserves to be addressed. I have reason to suspect that hydrochloric acid would not actually dissolve unobtainium any faster, but suspicion is not knowledge, and I can't rule out the possibility that HCl could do the job in five or six days.

Even if so, it doesn't invalidate my thesis. It's still useful to be able to skip the solution step! But I don't want to be dismissive. The examiner took the trouble to write substantive comments; protocol and general courtesy require a substantive answer. At the same time, I was hoping to avoid having to run another bunch of experiments.

Do I need to bite the bullet and go back to the lab, or is there a way to put a reasonable answer without being dismissive or evasive?

Congrats on minor corrections! It must such a relief.

I wouldn't worry. Justify your original reasons for using sulphuric acid and then say why you choose not to investigate other acids. I think you just need to acknowledge that he might be right but that his is also missing the point.

The correct and only way to deal with this sort of question and kill it stone dead is to say:-

"I thank the examiner for his interesting suggestion. This warrants further investigation and will form the next phase of this work".

I would then add a couple of sentences in the vein of what rewt has suggested above as regards why you chose H2SO4 and not other acids and a hypothesis about how you think HCl would compare. This is standard stuff to check that you've thought it through.