A ball is thrown up into the air. When it gets to the very top, what kind of energy does it have?

Density of salty water as compared to the density of pure water is(a) is less(b) is always equal(c) is always more(d) may be less or more

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

Select the correct answer. what does the process of natural selection involve?