This is science, so next time try asking in the science section.
5) Desks are solid unless you go to a jellyfish school. Solids have both definite shape and volume, so the answer there was A.
6 is correct, so I will help with 7.
7) A wave travels between the same medium, so it only transfers energy. Waves only transfer energy; the particles of matter in the medium return to their original position. The correct answer there was also A.
I got A for both, but it is always helpful to double check work. Hope this helps!
