The five successive ionization enthalpies of an element are 800, 2427, 3658, 25024 and 32824 kJ mol^–1. The number of valence electrons in the element is :

The atomic number of the element unnilennium is :

Three elements X, Y and Z are in the 3^rd period of the periodic table. The oxides of X, Y and Z, respectively, are basic, amphoteric and acidic. The correct order of the atomic numbers of X, Y and Z is :

In general the property (magnitudes only) that show an opposite trend in comparison to other properties across a period is