Please help.

For his science project, Austin wants to determine if the PH of standing rainwater changes over time. He collects a jar of rain water and places it indoors in a spot that does not receive a lot of sunlight to limit evaporation. Using a PH testing kit ,he measures the PH of the water once a day for 20 days.

What is the independent , manipulated , variable in Austin experiment?

Question

Please help. 

For his science project, Austin wants to determine if the PH of standing rainwater changes over time. He collects a jar of rain water and places it indoors in a spot that does not receive a lot of sunlight to limit evaporation. Using a PH testing kit ,he measures the PH of the water once a day for 20 days. 

What is the independent , manipulated , variable in Austin experiment?

anonymous · Answer

i HAVE NO IDEA..... sorry. try calculatorsoup.com

aaronq · Answer

The sentence "pH of standing rainwater changes over time" tells you what is what. 

you could say that if you made an equation for this it would be "$\sf pH(t)$", pH as a function of time. So, $t$ is the independent variable and pH is the dependent variable - it is dependent on the time.

anonymous · Answer

My guess is the number of days the rainwater is allowed to sit