In an exercise I am doing in 3/2, I am asked to mark the rests used as correct or incorrect. I got an answer wrong and am not sure why. Here is a photo of the answer book and you can see right at the end the dotted semibreve rest is marked as wrong. Can someone explain why, since three minims do fit into a dotted semibreve rest?
A Whole Bar rest which fills a bar in any (with a few extreme exceptions) time signature looks like a semibreve rest, but is centred in the bar. It's the standard notation.
It is arguable that a dotted semibreve rest would also be OK for a complete bar of 3/2.. But that would be positioned at beat 1 position in the bar, not centrally. I guess there MIGHT be a multi-voice situation where using one was justified? But it certainly wouldn't be the 'right answer' in a theory paper.
So I'm afraid your answer was doubly incorrect :-)
The rest that is used for a whole bar that rest is the semi-breve rest. The only exception to this rule is 4/2 time where a breve rest is used. A semi-breve is not a whole measure in 4/2, thus it is inadequate to show that the whole bar rests in that time signature.
Just for interest sake, your first answer in the picture is wrong because you don't use one rest over beats, you needed two crotchet rest instead of the minim.
Why was the first one marked wrong? Now, personally, I'd rather see two quarter-rests than one half-rest (and, gosh, isn't that easier to remember than "doublehalfsemicrochetquaverbreve" ? ) because the half-rest spans a beat in the time signature. But that just makes your answer clumsy, not wrong.
As to the final measure: again, to make it easier on the performer, it might be preferable to put in a whole-rest followed with a half-rest, so they don't have to think about what the time signature is at this point in the piece.