Does studying 15 minutes every night influence students' test scores? Identify the two controlled variables.

Is there a diagram/picture you can provide? it seems this question goes along with a

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom

Hcn is your answer my guy : )