On both of them this is physics not math

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

What tightening torque should be used for a hexagonal head screw (not split-bolt) on a 250 kcmil conductor?

If y gets smaller as x gets bigger and y have an relationship?