¿Cuál de las siguientes sustancias es un ejemplo de elemento químico? El ácido sulfúrico
El agua
El oro
El dióxido de carbono​

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?

What are the similarities of physical and chemical change ?

If one fission reaction of a uranium-235 atom produced two neutrons, how many neutrons would be released if the chain reaction occurred three more times?