The student performed an experiment to test his hypothesis about sunlight and plant height using two plants. He kept everything the same between two tomato plants except he exposed them to different amounts of sunlight. He also used a third plant as a control group, or a group in which no variables are manipulated to confirm the results. Roberto critiqued the work. Which problem did Roberto most likely identify? 1.The sample size is too small. 2.Too many variables are manipulated. 3.It is not possible to keep the conditions the same. 4.Controls should only be used in studies of animals.

The sample size is too small

Explanation:

In this case, the sample size refers to the number of plants in the experiment. Only one plant was assigned to each group. This sample size is too small to derive any statistically significant meaning from the outcome of the experiment.

If a larger sample size is used, a more accurate mean value will be obtained. It will also be easy to identify any outliers that could cause the data to be skewed if the sample size were to be smaller. Use of larger sample size decreases the margin of error in the experiment.

sure what is it? ^w^

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%