STD 11 - 3. Classification of elements and periodicity in properties — NEET STD 11 Science — Question

$(I)$ $H_5P_3O_{10}$            $(II)$ $H_6 P_4O_{13}$

$(III)$ $H_5P_5O_{15}$          $(IV)$ $H_7P_5O_{16}$

non-cyclic phosphates are 

$\frac{2}{3}A{l_2}{O_3} \to \frac{4}{3}Al + {O_2},{\Delta _r}G =  + 940\,kJ\,mo{l^{ - 1}}$

The potential difference needed for the electrolytic reduction of aluminium oxide ............... $\mathrm{V}$