Pls help me I don’t understand it’s for my science class. Plz check if correct and tell me wether each is element or compound

Astudent conducts an experiment to determine how the amount of water given to a plant affects its growth. what is the independent variable for this experiment?

Percent ionization for a weak acid (ha) is determined by the following formula: percent ionization=[ha] ionized[ha] initial×100%for strong acids, ionization is nearly complete (100%) at most concentrations. however, for weak acids, the percent ionization changes significantly with concentration. the more diluted the acid is, the greater percent ionization.a certain weak acid, ha, has a ka value of 9.4×10? 7.part acalculate the percent ionization of ha in a 0.10 m solution.part bcalculate the percent ionization of ha in a 0.010 m solution

True or false exosphere is the least dense