Inside a room, the air is often warmer near the ceiling then near the floor. which of the following accounts for this difference in temperature?

a radiation
b insulation
c convection
d conduction

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).

The phase where ice changes directly to gas is called sublimation 

Answer///an early form of the atomic theory; dalton atomic theory;

D. h2o + h2o > h3o + oh- confirmed.