Predict whether these concentrations would increase, decrease, or stay the same if ammonia-nitrifying bacteria were added to the sample

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

Hybrid instruments that play sounds that are part sampled and part synthesized are known as:

How have high taxes on tobacco products impacted the number of people who use them? a. the number of tobacco users has increased. b. the number of tobacco users has decreased. c. the number of tobacco users has not changed. d. the number of adolescent tobacco users decreased, while the number of adult users increased