Chemistry- Acids and Bases?

Question

Arrange the acids
I) phosphorous acid (H3PO3),
pKa1 = 2.00;
II) hydrogen selenate ion (HSeO-4 ),
pKa = 1.92;
III) selenous acid (H2SeO3), pKa = 2.46;
V) phosphoric acid (H3PO4), pKa = 2.12;
in increasing order of strengths.
1. Cannot be determined
2. IV, III, I, II
3. III, I, IV, II
4. IV, I, III, II
5. None of these
6. II, I, IV, III
7. III, IV, I, II
8. II, I, III, IV
9. II, IV, I, III
10. II, III, I, IV

Answer 1

7

Answer 2

the lower the pKa, the stronger the acid. HCl, for example, has a pKa of approximately -8. So, the order would be:

II, I, IV, III

Answer 3

Selenous