Select the correct answer from each drop-down menu. When Raymond observes certain natural phenomena, he often forms ideas about their causes and effects. Suppose that Raymond
surmises that leaves change color in autumn due to scarcity of sunlight. In order to test whether his idea is accurate, he must first
construct a falsifiable
that defines a clear relationship between two variables. Raymond's next step is to
that would isolate and test the relationship between the two variables. This task can be pretty
daunting because Raymond will need to identify and eliminate any
variables that could confuse test results.

the answer is d : ) have a good da

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

level 4 to level 2 : ))