Which compound is covalent?

1. CaCl2
2. N20
3. NaBr
4. KF

Gymnast always perform on padded mats. how does the mats protect the gymnast

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.

Helium decays to form lithium. which equation correctly describes this decay?