Pure substances contain only one type of a. atoms only. b. molecules only. c. atoms or molecules. d. mixture.

Pure substances contain atoms only. You cannot break down a pure substance.  An element is always uniform all the way through. An element CANNOT be separated into simpler materials except during nuclear reactions.

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.