Question

1. elements vs. compounds

each of these options is either an element or a compound. which are elements? (select all that apply)
a. a molecule with two oxygen atoms
b. an atom of krypton
c. a molecule with two phosphorus atoms and five oxygen atoms
d. a molecule composed of one type of atom
e. a molecule composed of more than one type of atom

1. solute and solvent identification

which answer choice correctly identifies the solute and solvent in this example?
a. water is the solvent, and sugar is the solute.
b. sugar is the solvent, and water is the solute.
c. water and sugar are both solvents; the finished solution is the solute.
d. water and sugar are both solutes; the finished solution is the solvent.

1. increasing rate of dissolution

which of the following illustrations would not increase the rate of dissolution of solid solutes in aqueous solutions?
a. 4 only
b. 1 and 2 only
c. 1, 2, and 3 only
d. 1, 2, 3, and 4

1. diluting a saltwater solution

12 g of nacl (salt) are dissolved into 50 ml of water at room temperature. how could the saltwater solution be diluted?
a. the solution cannot be diluted.
b. to dilute the solution, add more salt and water in the original proportion.

Explanation:

1. Elements are pure substances with one type of atom. A (O₂), B (Kr atom), D (single atom type) are elements.
2. Solvent dissolves solute; water (solvent) dissolves sugar (solute).
3. Rate of dissolution increases with stirring, heating, surface area. "4" does not.
4. Dilution requires adding solvent (water) to lower concentration.

Answer:

1. A. A molecule with two oxygen atoms, B. An atom of Krypton, D. A molecule composed of one type of atom
2. A. Water is the solvent, and sugar is the solute.
3. A. 4 only
4. (Note: No correct option listed; dilution requires adding water. Assuming intended, the answer would involve adding water, but based on given options, none are correct. However, if forced to choose from provided, no valid answer.)