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 :

The major product obtained from E₂ - elimination of 3-bromo-2-fluoropentane is

The number of subshells associated with n = 4 and m = –2 quantum numbers is

If you spill a chemical toilet cleaning liquid on your hand, your first aid would be