What are covalent compounds composed of?
a. a metal and a metal
b. a metal and a non metal
c. a nonmetal and a nonmetal
d. an alkali metal and a nonmetal

Can someone me with these questions plz.

Schrodinger and heisenberg developed an alternate theory about atomic nature that contradicted some of bohr's model of the atom. how do changes resulting from new technology and evidence affect the reputation of the atomic theory?

The number of neutrons is equal to the atomic number minus the atomic mass. a. true b. false