We can dilute an aqueous solution by adding liquid water to the solution, resulting in a less concentrated solution. Which of the following would result in a more concentrated solution?

(A) decreasing the number of moles of solute
(B) adding ice to the solution and allowing the ice to melt
(C) evaporating some of the water contained in the solution
(D) none of the above

= C

Explanation:

evaporating some of the water contained in the solution will increase the concentration of the resulting solution, because there will be concomitant increase in the number of moles of the solute left in the solution.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6