Distinguish between "conduction", "convection" and radiation as related to heat transfer.

Conduction occurs when a substance is transferring heat via touching.
Convention occurs when the substance being heated begins a cycle of cooling and heating. the heat goes to the opposite side of which the substance is being heated and the substance is cooled on the corresponding side, this cycle continues until the heat source is extinguished.
Radiation occurs when the heat of a substance is being transferred via gas form. Ex: sunburn.

B. convex since the words are bigger

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -