Which of the following oxy acids of phosphorus is a reducing agent and monobasic?

Which of the following are the correct orders of stability of oxidation states of cations?
$(a) \ Pb^{+2} > Pb^{+4}, Tl^{+1} < Tl^{+3}$
$(b) \ Bi^{+3} < Sb^{+3}, Sn^{+2} < Sn^{+4}$
$(c) \ Pb^{+2} > Pb^{+4}, Bi^{+3} > Bi^{+5}$
$(d) \ Tl^{+3} < In^{+3}, Sn^{+2} > Sn^{+4}$
$(e) \ Sn^{+2} < Pb^{+2}, Sn^{+4} > Pb^{+4}$
$(f) \ Sn^{+2} < Pb^{+2}, Sn^{+4} < Pb^{+4}$

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{N}_2O_5 + H_2O \longrightarrow 2HNO_3$

Amongst the following compounds:
$I.$ $H_5P_3O_{10}$
$II.$ $H_6P_4O_{13}$
$III.$ $H_5P_5O_{15}$
$IV.$ $H_7P_5O_{16}$
Which of these are non-cyclic phosphates?

Which of the following compounds releases nitrogen dioxide $(NO_2)$ upon heating?

Which of the following oxides is most acidic?