Thought cannot be performed or produced by a cell as it is devoid of a capable nerve system and hence it does not get any information and thus cannot produce any thought.
Using the mass/volume percentage method for percentages of the solution, you simply divide the grams of solute by the volume of the solution and multiply by 100 to get your percentage.
(75.0g/250mL)•100 = 30.0% solute
The answer for question 14 would be C and question 15 is B