"2+2=?" or "What is the capital of Ohio?
are normally described as
General knowledge has been defined in differential psychology as "culturally valued knowledge communicated by a range of non-specialist media" and encompassing a wide subject range. This definition excludes highly specialized learning that can only be obtained with extensive training and information confined to a single medium.
or General Reference
General Reference questions are questions that can be fully answered with a single link to a place that is specifically designed to provide the information in the question. These sources include online dictionaries [also thesauruses] or etymology sites.
Writing Good ‘Meaning’ Questions EL&U Community Blog
or Literal Questions
Literal questions ask for answers that are specific and can be confirmed and therefore agreed upon by many people. Examples include: "What time does the concert start?" "What size do you wear?" "What references did you use to write your paper?" and "What do two and two total?
What are Literal & Inferential Questions? eHow.com
Mental Floss offers thirty quiz-type questions, which cover
• biology: What part of the body produces insulin? • physics: What chemical element is diamond made of? • literature: Who wrote 'The Scarlet Letter'? • geography: Name a US state beginning with K. • television: Who did Matthew Perry play in 'Friends'? • animation: What type of animal is Bambi? • vocabulary: What is the name of the 'tool' needed to play snooker or billiards to hit the ball? etc.
These questions have two things in common:
- There is only one correct answer.
- They do not require expert knowledge.
Nowadays, the answers to these type of questions are easily found on the Internet, you don't need to know the answers. But for exams, and quiz shows such as Jeopardy, individuals must have this type of knowledge at their fingertips. Jeopardy offers a twist inasmuch as contestants are first given the answers to which they must supply the questions.
General knowledge/reference questions are unsuitable for the SE format, precisely because it is an online Q&A website. The SE model would cease to exist if every question only had one correct answer. It's precisely because there isn't one clear-cut answer that many users post a question. They are ‘lost’ in a labyrinth of over-information and contradictory explanations.
As a reminder, the questions listed above, all conform to the criteria asked by the OP
questions with a known, single, unambiguous, objective, and correct answer
Take for example this single-word-request type question, which could be found on EL&U:
What is the name of the 'tool' needed to play snooker or billiards to hit the ball?
It's a good description, easily understood, and it has one clear unequivocal answer in English. But is it a good fit for the SE model? No, it isn't. Because if you don't already know the answer, you can find out just by searching the terms snooker and billiards and visiting the corresponding Wikipedia pages. All that is required is a bit of research (if you don't already know the answer), and speed to be among the first to post an answer.
The ideal questions on EL&U are those which encourage the best explanations. But even that doesn't necessarily equate with being high-level.
Take for instance this simple question: What is the name of a small unluxurious restaurant?. Despite it being a general knowledge/reference/literal question there isn't one correct answer. In fact eighteen answers were posted and with the exception of one, all of them have been upvoted, which means there are at least 17 possible answers to that single question. The top three answers earned more than fifty upvotes each, which surely suggests that there are at least three ‘correct’ answers. The top answer has so far received 113 upvotes, which according to the SE model, makes it the best.
In answer to the OP's final request
If you wanted to describe the kinds of questions StackExchange welcomes and encourages in as few words as possible (ideally two: adjective + "questions"), what would you say?
I would suggest: stimulating questions, the “why” questions whose answers you cannot find in one single resource, questions that teeter perilously on the POB (primarily opinion-based) edge. Yet SE would probably prefer convergent questions, I think it typifies the SE model.
convergent question by its nature has a more narrowly defined correct answer – the answer is
generally short, requires little reflection and requires that the responded recall from memory a bit
of factual information. Convergent questions may also be referred to as “closed-ended”
questions, meaning that the instructor is looking for an anticipated response that requires little original thought on the student’s part. Convergent questions will not require students to put original thought to the development of an answer. In other words, the answer will have been
provided within the context of the lecture or readings assigned by the instructor.
Asking More effective Questions
William F. McComas and Linda Abraham
Wikipedia has this to say on convergent thinking
Convergent thinking is the type of thinking that focuses on coming up with the single, well-established answer to a problem. It is oriented toward deriving the single best, or most often correct answer to a question. Convergent thinking emphasizes speed, accuracy, and logic and focuses on recognizing the familiar, reapplying techniques, and accumulating stored information. It is most effective in situations where an answer readily exists and simply needs to be either recalled or worked out through decision making strategies. A critical aspect of convergent thinking is that it leads to a single best answer, leaving no room for ambiguity. In this view, answers are either right or wrong.
Here's a diagram that illustrates the concept.
A third source defines convergent questions as:
Answers to these types of questions are usually within a very finite range of acceptable accuracy. These may be at several different levels of cognition — comprehension, application, analysis, or ones where the answerer makes inferences or conjectures based on personal awareness, or on material read, presented or known.
Five Basic Types of Questions Leslie Owen Wilson, Ed. D
The latter appears to be a duplicate of The University of New South Wales website article UNSW What is questioning? The irony is that Wilson placed this symbol © next to his name, suggesting he is the intellectual proprietor. Who copied whom I don't know, so in fairness I shall post both sources.