Question

which objective would you use if the distance between it and the slide being observed is the least?
high power
low power
oil immersion
scanning
question 16
which of the following procedures should you perform before using the microscope?
clean all lenses with lens paper.
plug the microscope into an outlet and turn the light on.
the objective should be turned to scanning power.
all of the above

Explanation:

For Question 15: Microscope objectives with higher magnification have shorter working distance (distance to the slide). Oil immersion is the highest magnification option here, so it has the least distance to the slide.
For Question 16: Proper pre-use microscope steps include cleaning lenses to remove debris, powering on the light source for illumination, and setting the objective to the lowest power (scanning) for easy initial focusing. All these steps are necessary.

Answer:

Question 15: Oil immersion
Question 16: All of the above