Can voltaic cells have a negative electric voltage?

Your friend offers to show you an intrusive igneous rock. which of the following would you expect to see?

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?

Why is nh3 classified as a polar molecule