Миска с супом стоит на столе.

with

Breakdown of Миска с супом стоит на столе.

• стоять: to stand
• стол: the table
• на: on

Questions & Answers about Миска с супом стоит на столе.

Which case is миска in, and why isn't it миску or миски?

миска is in the nominative case because it’s the subject of the sentence (“the bowl does something”).

• миску would be accusative, used if the bowl were the object of an action (“I see the bowl”).
• миски could be genitive (“of the bowl”), dative (“to the bowl”), or nominative plural, none of which fit here.

Why is there a с before супом, and why is суп in the form супом?

The preposition с meaning “with” requires the instrumental case.

• суп (soup) in instrumental becomes супом (“with soup”).
• So с супом literally means “with soup.”

Can I say миска супа instead of миска с супом, and what’s the difference?

Yes, миска супа is also possible and uses the genitive (супа) to indicate the content (“a bowl of soup”).
Nuance:

• миска супа = “a bowl of soup” (focus on the portion of soup).
• миска с супом = “a bowl with soup” (focus on the bowl that contains soup).