RRB Non Technical Model Papers 9 with solutions

(4) The 18 groups in the periodic table are numbered from 1 to 18 according to IUPAC convention. However, according to American convention,these are also denoted by IA ,IIA, IIIB, IVB, VB, VIB, VIIB,VIII (which actually includes 3 groups), IB ,IIB, IIIA, IVA, VA,VIA, VIIA and 0 (zero). This is based on maximum valency shown by elements in the group.