7 valance electrons and a atomic number of 9
PH + pOH = 14
pH + 0.253 = 14
pH = 14 - 0.253
pH = 13.747
[ H+] = 10 ^ -pH
[ H+ ] = 10 ^- 13.747
[ H+ ] = 1.790x10⁻¹⁴ M
hope this helps!
Answer:
D.) The nuclear model describes the atom as a dense, positive nucleus surrounded by a cloud of negative electrons.