13. what salt results from the neutralization of phosphoric acid with potassium hydroxide? 14. what is the oxidation number of chlorine in al(clo4)3? 15. which element is oxidized in the following reaction: cuo(s) + h2 (g)  cu(s) + h2o (l)

13) phosphoric acid + potassium hydroxide

H3PO4 + 3 KOH > K3PO4 + 3H2O

H3PO4 ( acid )

KOH ( base )

K3PO4 ( salt )

Therefore fore K3PO4 is salt ( tripotassium phosfate )

14) Al(ClO4)3

Al⁺³ ClO₄⁻

in chlorine = x + ( - 2 * 4 ) = -1

x - 8 +1 = 0

x = 8 - 1

x = +7

in Al(ClO4)3 chlorine oxidation state + 7

15) CuO(s) + H2 (g)  Cu(s) + H2O (l)

The oxidation state of Cu in CuO  = +2

The oxidation state of H in H2 = 0

The oxidation state of Cu in Cu = 0

The oxidation state of H in H2O = +1

That in the above reaction  , The oxidation state of Cu is decreased from +2 to 0  , so Cu⁺² is reduced , The oxidation state of H  is decreased from 0 to +1 ,  So H2  is oxidized .

Hope that helps!

c) should be the answer.