Why does common table salt (nacl) have a high melting point?

Substance x has a fixed volume, and the attraction between its particles is strong .substance y had widely spread out particles and can be compressed what can most likely be concluded about these substances

__can be defined as which velocity changes

The alkali metals (group 1) consist of lithium (3), sodium (11), potassium (19), rubidium (37), cesium (55), and francium (87). they are soft, metallic solids with low densities and low melting points. based on the data shown in figure 1, how many valence electrons do alkali metals share?