Idon't seem to understand how to solve this one question, can anyone pease me out?

Working with si (metric) units for each of the following commonly used measurements, indicate its symbol. liter gram milliliter kilogram meter centigram milligram centimeter kilometer second millimeter milliseconds

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

The chemical bond connecting one nucleotide with the next one along the nucleic acid chain is called a