For a certain experiment, Juan must measure the concentration of a certain substance in a solution over time. He needs to collect a measurement every 0.05 seconds. He then needs to display his data in a graph and place that graph in a text document. Select the best tools to use for this experiment. Check all that apply.

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

Determine the maximum r-value of the polar equation r =3+3 cos 0

If the specific heat of a metal is 0.850 j/g °c, what is its atomic weight?