AgBr → in NH3 (Solubility increases, due to stable complex)
AgBr is highly soluble in ammonia due to complex formation. → in 0.1 M AgNO3 (Solubility decreases due to common ion effect) → in 0.2 M NaBr (Solubility decreases more due to common ion effect) → in pure water (Normal dissociation)
Hence, the order is:
(iii) < (ii) < (iv) < (i)