Final answer:
Mashed potatoes are not suitable for a full liquid diet because they are semi-solid and require chewing, unlike other items that are liquid at room temperature.
Step-by-step explanation:
A patient on a full liquid diet can have liquids or foods that are liquid at room temperature. This includes items like ice cream, tomato soup, and coffee. However, mashed potatoes are not generally considered appropriate for a full liquid diet because they have a semi-solid consistency that requires chewing and may not be easily swallowed like true liquid items. The full liquid diet is often prescribed for patients who are recovering from certain surgeries or have difficulties with solid foods.
Ice cream is allowed because it melts at room temperature; tomato soup and coffee are inherently liquid and thus also acceptable. Mashed potatoes can be prepared to a thin consistency that can be easily consumed on a full liquid diet. Coffee, if it is without solids, can also be consumed on a full liquid diet.