SELECT ... FROM tbl ... ORDER BY RAND() LIMIT 10;
gets you a random 10. But this is not sufficient to avoid repeating some of them for the next 10. So let's get a bit more sophisticated. Let's prime the random number generator (with a "seed") so that the sequence is repeatable, then use OFFSET to pick which 10.
If this is being handled by web pages, then the seed must be passed from one page to the next, similar to how you use to decide that it is time for the "next 10" questions.
Assuming you don't care if the sequence repeats itself for a second...
$seed = SELECT UNIX_TIMESTAMP();
SELECT ... FROM tbl ORDER BY RAND($seed) LIMIT 10 OFFSET $offset;
Then remember $seed, but increment $offset by 10 for the next 'page'.
You, of course, need some way to stop after you run out of questions.