When the first element of the periodic table is treated with dioxygen , it gives a compound whose solid state floats on its liquid state. This compound has an ability to act as an acid a well as a base. What product will be formed when this compound undergoes autoionisation ?

When the first element of the periodic table is treated with dioxygen

1.	When the first element of the periodic table is treated with dioxygen , it gives a compound whose solid state floats on its liquid state. This compound has an ability to act as an acid a well as a base. What product will be formed when this compound undergoes autoionisation ?
Answer» Solution :The first element of the periodic table is H and its molecular FORM is dihydrogen `(H_(2))` . When dihydrogen reacts with dioxygen , water is formed. Water is a liquid at room temperature . When liquid water freezes,it expnads to form ice . In other words, density of ice is lower than that of liquid wter and hence ice floats over water. Water is amphoteric in nature, i.e., it acts as an ACID in presence of strong bases and a base in presence of strong acids. `UNDERSET("Acid"_(1))(H_(2)O(l))+ underset("Base"_(2))(NH_(3)(aq)) to underset("Acids"_(2))(NH_(4)^(+)(aq))+ underset("Base"_(1))(OH^(-)(aq))` `underset("Base"_(1))(H_(2)O(l))+ underset("Acid"_(2))(H_(2)S(aq)) to underset("Acids"_(1))(H_(2)O^(+)(aq))+ underset("Base"_(2))(HS^(-)(aq))` Due to amphoteric CHARACTER, water undergoes self ionization as shown below : `underset("Acid"_(1))(H_(2)O(l))+ underset("Base"_(2))(H_(2)O("base")) to underset("(CONJUGATE acid)")underset("Acids"_(2))(H_(3)O^(+)(aq))+ underset("(Comjugate base)")underset("Base"_(2))(OH^(-)(aq))` This self ionization of water is called auto-protolysis.