What is the golden standard for scientific research?

Randomized controlled trials have long been held up as the “gold standard” of clinical research. ... In a randomized controlled trial (RCT), participants are randomly assigned to receive either the treatment under investigation or, as a control, a placebo or the current standard treatment.

Explanation:

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the answer to this is : 50 elements

EXPLATION:

The concept of a systematic measure for atomic weights greatly contributed to the success of Mendeleev's periodic table. In (1864) in with about 50 elements known,The mass of an atom in theA.M.U. is roughly equal to the sum of the number of protons and neutrons in the nucleus in the atom . The A.M.U. is used to express the relative masses of, and thereby differentiate between, various isotopes of elements.

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