Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: The protist kingdom is sometimes called the "trash can" kingdom. It includes all eukaryotes that don't fit in one of the other three eukaryote kingdoms: Animalia, Plantae, or Fungi. There are thought to be between 60,000 and 200,000 protist species. Many have yet to be identified. The protist kingdom is very diverse, as shown in Figure below . Answer: trash can kingdom

Answer: What is the protist kingdom sometimes called as?

Question: Passage: An ideal engine, the most efficient theoretically possible, is called a Carnot Engine. Its efficiency is given by the following formula, where the temperatures are, respectively, the temperature of the exhaust environment and the temperature of the heat input, in Kelvins. In a Carnot engine heat is input and exhausted in isothermal cycles, and the efficiency is . In all real engines heat is lost to the environment, thus the ideal efficiency is never even close to being obtained. Answer: carnot engine

Answer: What is the name of the the most efficient possible engine?

Question: Passage: Physical properties include color, density, hardness, and melting and boiling points. Answer: physical

Answer:
Hardness, density, color, and melting and boiling points are all considered what types of properties?