D-Fructose is the sweetest monosaccharide. How does the Fischer projection of D-fructose differ from that of D-glucose?

The projection of the Fisher projection of D-Fructose and D-glucose is that  The carbonyl carbon in D-glucose is carbon 1 (aldehyde), whereas in D-fructose, the carbonyl group is on carbon 2 (ketone).

Explanation:

An aldehyde is a compound containing a functional group with the structure −CHO, consisting of a carbonyl center and

A ketone is a functional group with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents.

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.