Learn Russian: Мне интересно, почему поднос стоит на диване. - I wonder why the tray is standing on the sofa.

In Russian, objects with a functional flat base that they are resting on, like plates, cups, glasses, and trays, are considered to "stand" (стоять). If the tray were thrown upside down or leaning on its edge, you would use лежать (to lie) instead.

Could I use ставит instead of стоит here?

No. Стоит (from стоять) describes the state of the tray already being in a location. Ставит (from ставить) means "puts" or "places" and requires a person doing the action to an object. Since the tray is just resting there on its own, we use the intransitive state verb стоять.

Why does "I wonder" translate to Мне интересно instead of starting with Я?

Russian often uses the Dative case for states of mind or feelings. Мне is the Dative form of я. The phrase literally means "To me it is interesting." This is the standard, natural way to express "I wonder" in Russian.

The lesson mentions using the Accusative case with verbs like placing or putting. Why is it на диване (Prepositional) here?