In effect of concentration on rate, why is it important to
havethe same potassiumin four reaction mixtures?

Explanation:

If we change the concentration of Potassium since we take KI solution, concentration of I- changes, then the rate changes accordingly

Rate = k[H2O2 ]^a[I-]^b [H+]^c

The concentrations of I- and H+ are held constant in the procedure

thus to study the rate of the reaction, concentration of KI solution has to be constant only the peroxide solution varies.

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be