Lithium shows anomalous behaviour where it shows similar properties to alkaline earth metals, known as diagonal relationship. This is due to the exceptionally small size of the atom. Anomalous behaviour is also due to the high polarising power of the lithium ion. Polarisation is the distortion of electron cloud of the anion by the cation. Options (iii) and (iv) are also properties of lithium but they are also properties of alkali metals. The correct answers are (i) and (ii).