How many molecules are in 1.28 mols of silicon dioxide​

7.71x10^23 molecules

Explanation:

Avogadro's # = 6.022x10^23

1.28 mol SiO2 x 6.022x10^23/ 1 mol SiO2 = 7.71x10^23 molecules

sodium (na), for example, has one electron in its valence shell. this is an unstable state because that valence shell needs eight electrons to be full. in order to fill its valence shell, find a way to add seven electrons to its valence shell

the answer to your question is c