Asolution is formed when the solute uniformly disperses throughout (or dissolves in) the solvent. the process can be described by three steps:

1. separation of solvent-solvent particles (aka expanding the solvent),

2.separation of solute-solute particles (aka expanding the solute), and

3. formation of solute-solvent interactions.

classify the steps involved in the formation of a solution as being endothermic or exothermic.

a. step 1 is exothermic, step 2 is exothermic, step 3 is endothermic

b. step 1 is endothermic, step 2 is endothermic, step 3 is exothermic

c. step 1 is endothermic, step 2 is exothermic, step 3 is exothermic

d. step 1 is exothermic, step 2 is endothermic, step 3 is exothermic

B. Step 1 is endothermic, Step 2 is endothermic, Step 3 is exothermic

Explanation:

Prior to the formation of a solution, the solvent molecules attract each other as well as the solute molecules. For a dissolution to be effective, those interactions need to be weakened, at the same time that interaction between solute and solvent ought to be established. The formation of solute-solvent interactions is exothermic and provides the energy required to separate solvent-solvent particles and solute-solute particles, being both processes endothermic (the absorbed energy is used to break the interactions).

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.