CO2 NaCl
HCl

These may all be classified as
A) elements and compounds.
B) elements and molecules
C) elements and pure substances.
D) compounds and pure substances

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.