SCN- is a weak field ligand while CN- is a strong field ligand
Explanation:
The spectrochemical series is an arrangement of ligands according to their magnitude of crystal field splitting. Ligands that cause only a small degree of crystal field splitting are called weak field ligands while ligands that cause large crystal field splitting are called strong field ligands.
Strong field ligands often lead to the formation of low spin complexes with the least number of unpaired electrons while high spin complexes are formed by weak field ligands.
CN- is a strong field ligand as it lies towards the right hand side of the spectrochemical series.
SCN- is a weak field ligand hence it forms a high spin complex having the maximum number of unpaired electrons for Fe^3+, hence the answer.
Explanation: Hydroxide, any chemical compound containing one or more groups, each comprising one atom each of oxygen and hydrogen bonded together and functioning as the negatively charged ion OH-.
Explanation: The -OH bond absorbs IR and vibrates at a characteristic and many times distinctive wave number of 3500cm-1. The -C=O would vibrate at 1700cm-1 though not clearly because -C-O bond typically vibrates around this point
