Answer:
Xe
Explanation:
Cs and Na are solids in room temperature while F and Xe are gases.
The number of electrons in the outermost shell of an atom will determine its reactivity. Out of the gases given Xe and F, F ( the most electronegative element) posses 5 valence shell electrons which makes it highly reactive while Xe which is a noble gas posses 8 valence shell electrons which makes it less reactive compared to many elements.
Answer:
1.2 stands for 2 atoms of hydrogen and 1 atom of oxygen
2.carbon and oxygen
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I believe the answer is a Meander. (beware that this is actually a geography question not a biology one, please put it in the right section next time and it will be answered quicker!)
The answer is single nucleotide polymorphisms (SNPs)
It checks for variation in nucleotide sequences in particular genes that may be different among people, especially in different races. An example is a gene for melanin that would determine the trait for skin color. Single nucleotide changes in the gene between population can be used to differentiate populations.