Answer:
C
Explanation:
As the Earth moves in relative to the moon the Earth blocks part of the sun from the moon causing only parts of the moon to light up. This BEST answers the question because B is not accurate because it doesn't describe why we actually SEE it. A might be true but it is not the BEST explained.
Hope this helps! (^-^)
B. An atom whose nucleus is unstable and emits particles and and energy. This is a Radioactive isotope.
The atomic nuclei of constituent atoms of the same element include the same number of protons but different numbers of neutrons. Radio isotopes are an element's radioactive isotopes. They can alternatively be described as atoms with an excess of energy in their nucleus or atoms with an unstable ratio of neutrons to protons. A radioisotope's unstable nucleus can form either spontaneously or as a result of a deliberate alteration of the atom. Radioisotope production can occur using either a cyclotron or a nuclear reactor. Molybdenum-99, which has a high neutron content, can be produced most effectively in nuclear reactors, whereas fluorine-18, which has a high proton content, can be produced most effectively in cyclotrons. Uranium is the most well-known illustration of a radioisotope that is found naturally. Uranium-238 constitutes all naturally occurring uranium with the exception of 0.7%.
Learn more about Radioisotopes
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Classification systems previously were having very different goals than modern classification systems. If we look at old eras, scientists like Aristotle and Theophrastus tried to classify organisms on the basis of apparent characteristics, habitat and simple other traits.
Old classification systems had alot of errors and flaws. For example they classified fish and whale in one group because they lived in water, now we know fish is amphibian while whale is mammal.
So we can say that the goal o earlier classification system were just to make groups of organisms on the basis of External features.
Goal of modern classification system:
Modern classification approach was started by Linnaeus. It focuses more on biological delimitation and evolutionary histories than mere external characteristics. It organizes organisms in groups in such a way that grouping reflects their evolutionary relatedness. It is not just specie level but also focuses on sub-specie and population level classification.
Thus modern goal is better in many terms and is more reliable than old classification goals.
Hope it helps!
Answer:
Vertebrates are further classified according to several criteria like exoskeleton, respiratory organs, method of giving birth, number of chambers in heart, mode of living etc. They are further classified into classes Pisces, Amphibia, Reptilia, Aves and Mammals
A control group take no part in any experiment, they simply do what they do normally in order to compare the results from someone who has done something differently (experiment) and someone who hasn't. Hope this helps
