$\Delta \text { hyd } H ^{\circ} \text { of } Cu ^{2+}( aq )=-2121\,kJ\,mol ^{-1}$
$\Delta_{ i } H _1^0$ of $Cu =+745\,kJ\,mol ^{-1}$
$\Delta_{ i } H_2^{\circ} \text { of } Cu =+1960\,kJ\,mol ^{-1}$
$[Cr = 24, Mn = 25, Fe = 26, CO = 27]$
(પ. ક્ર. $Ce = 58,\,Lu = 71,\,La = 57,\,Yb = 70$ )
............ $BM$ છે (નજીકનો પૂણાંક)
(આપેલ : પરમાણુ ક્માંક $\mathrm{V}=23, \mathrm{Mn}=25, \mathrm{Cr}=24$ )