Whats the answer of dependent variables and independent varies

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Name the intersection of plane bpq and plane cpq.

Which statement explains why the bonds between non metals tend to be covalent? the bonds are found to be nondirectional they have large differences in electronegativity they have small differences in electronegativity they have ions that produce an electrostatic pull