Question

more experimental design practice
an apple is cut into slices. half of the slices are sprayed with lemon juice. all slices are stored in a sealed plastic bag. after 4 days, they are observed to see how brown they turned.
the independent variable is
the dependent variable is

Explanation:

The independent variable is the factor manipulated in an experiment. Here, lemon juice application is controlled (half sprayed, half not). The dependent variable is what is measured; browning level depends on lemon juice presence.

Answer:

The independent variable is: Whether the apple slices are sprayed with lemon juice
The dependent variable is: How brown the apple slices turned