Randomise 2 blocks of questions

Yes, you can either show blocks based on certain criteria (by using a branch in the survey flow and saying only show this block if this criteria is met) or randomize two blocks for anyone taking the survey like you mentioned. Either are done in the survey flow section.
To randomize the blocks you can use this article - https://www.qualtrics.com/support/survey-platform/survey-module/survey-flow/standard-elements/randomizer/

• If you have two blocks and only want to show one of them, just enter a '1' of course to show only one of them. And put the blocks to randomize under the randomizer.


• And then it will ask if you want to evenly present them or you can show one more than the other if wanted.