Determine which choice(s) is/are correct? i. stirring slows down (decreases) rate of dissolution. ii. grinding solids increases their surface area of contact. iii. heating slows down (decreases) rate of dissolution. iv. grinding solids speeds up their rate of dissolution.

II. Grinding solids increases their surface area of contact and IV. grinding solids speeds up their rate of dissolution.

Grinding solids greatly increases their surface area of contact. The solvent molecules can dislodge more surface particles in a given amount of time, so the rate of solution increases.

Heating increases the rate of solution because the solvent molecules have greater kinetic energy. They hit the surface of the solid with greater force and are better able to dislodge the solute particles.