what is pure substance.
Answers
Answer:
A pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample. Mixtures are physical combinations of two or more elements and/or compounds. Mixtures can be classified as homogeneous or heterogeneous.
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Black hole:-
A black hole is a region of space time where gravity is so strong that nothing-no particles or even electromagnetic radiation such as light-can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a blackhole.
White hole:-
In generally relativity,a white hole is a hypothetical region of spacetime and singularity which cannot be entered from the outside , although energymatter,light and information can escape from it. White holes appear in the theory of eternal black holes.