The correct option is B ∧∘m(NH4Cl)+∧∘m(NaOH)−∧∘m(NaCl)
According to kohlrausch’s law
the value of equivalent conductance at infinite dilution for any electrolyte is the sum of contribution of its constituent ions.
So
∧∘m(NH4OH)=∧∘mNH+4+∧∘mOH⊖...(1)∧∘m(NH4Cl)=∧∘mNH+4+∧∘mCl⊖...(2)∧∘m(NaOH)=∧∘mNH+4+∧∘mOH⊖...(3)∧∘m(Nacl)=∧∘mN++∧∘mCl⊖...(4)
Eq (1) = Eq(2) + Eq(3) – Eq(4)
Therefore ,
∧∘m(NH4Cl)+∧∘m(NaOH)−∧∘m(NaCl)