What type of reaction is this? Pb + 2NaCl → PbCl2 + 2Na

Which of the following statements is not true? • a. covalent compounds have low melting and boiling points. • ob. covalent bonds between atoms of a compound are relatively weak compared to bonds between molecules. • c. covalent bonds occur between nonmetals. • d. covalent compounds are often gases or liquids.

Does the energy in a solid increase or decrease when changing to a liquid?

The mass of a neutron is equal to the mass of a proton plus the mass of an electron. true or false false true