The molecular weight of the compounds (I)${\mathrm{Na}}_2{\mathrm{SO}}_4$

(II) ${\mathrm{Na}}_3{\mathrm{PO}}_4\cdot 12{\mathrm{H}}_2\mathrm{O}$ and  (III) ${\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2$ respectively are X, Y and z the correct set of their equivalent weights will be :

 $n=$Total charge of cation or total charge of anion
If reaction is given (with a salt not a redox reaction)
Then V.F. $n=$ no. of charges (+ve/-ve) being displaced or taking part in reaction :
(a) ${\mathrm{Na}}_2{\mathrm{SO}}_4{E}_{{\mathrm{Na}}_2{\mathrm{SO}}_4}=\frac{X}{2}$

(b) ${\mathrm{Na}}_3{\mathrm{PO}}_{4}12{\mathrm{H}}_2\mathrm{O}{E}_{{\mathrm{Na}}_3{\mathrm{PO}}_4}=\frac{Y}{3}$

(c) ${\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2{E}_{{\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2}=\frac{Z}{6}$