I have 4 Entities that are related - Student, Course, Teacher, and Classroom. My question is "Is it a Quaternary situation where all these entities are related in only one table containing their respective Primary Keys as foreign keys in a fifth table?".

I would appreciate ur response

Seems unlikely: if Teacher T1 teaches Student S1 for Course C1 in Classroom R1, isn't it likely that he teaches all his C1 students in R1?
In other words, Course, Teacher -> Classroom