What is an inappropriate action when giving montelukast granules?

Storing any mixed medication in the refrigerator is inappropriate because montelukast granules should be administered shortly after they are prepared. Once mixed with a food substance, they are intended to be consumed immediately to ensure proper dosing and effectiveness. Storing mixed medication may lead to degradation of the active ingredient or compromise the dose efficacy, making it less effective when it's finally consumed.

The other actions listed are appropriate: mixing granules with a small amount of apple sauce is a common practice to make administration easier, administering within 15 minutes ensures the medication remains effective, and using clean utensils each time prevents contamination and ensures the correct dose is given.