Answer:
The correct answer is-
Hypothesis: Antibiotics cause weight gain in cows.
Independent Variable: Antibiotic pill
Dependent Variable: Weight of cow
Control Group: a group of cows gets a placebo pill
Experimental Group: a group of cows gets an antibiotic pill
Explanation:
The Independent variable is the variable that causes the response from the dependent variable or affects the dependent variable in this study the antibiotic pill affects the weight of cows so The independent variable is an antibiotic pill and the dependent variable is the weight of cows.
The control group is the group of subjects that did not get the treatment in a scientific study in the case of this study group of cows that receives the placebo pill is the control group and the experiment group is subjects that receive the treatment which is a group with the antibiotic pill.
First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst. hope this helps :)
The answer is Nutrients the plant needs
