The periodicity is related to the electronic configuration. That is, all chemical and phyical properties are a manifestation of the electronic configurfation of the elements. The atomic and ionic radii generally decrease in a preiod from left or right. As a consequence , the ionisation enthalpies generally increase and electron gain enthalpies become more negative across a period. In other words, the ionisation enthalpy of the extreme left element in a period is the least and the electron left element on the extreme right is the highest negative. This results into high chemical reactivity at two extgremes and the lowest in the centre. Similarly down the group, the increase in atomic and ionic radii result in gradual decrease (with excetption in some third period elements) in electron gain enthalpies in the case of main group elements . These properties can be related with the (i) reducing and oxidising behacviour of the elements (ii) metallic and no-metallic charcter of element (iii) acidic, basic , amphoteric and neutral character of the oxides of the elements. Among `Al_(2)O_(3), SiO_(2),P_(2)O_(3)` and `SO_(2)` the correct order of acid strenght is :A. `Al_2O_3lt SiO_2ltSO_2lt P_2O_3`B. `SiO_2ltSO_2ltAl_2O_3ltP_2O_3`C. `SO_2ltP_2O_3ltSiO_2ltAl_2O_3`D. `Al_2O_3ltSiO_2ltP_2O_3ltSO_2`