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 as well as a base. What products 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 as well as a base. What products will, be formed when this compound undergoes autoionisation ?
Answer» Solution :The first element of the periodic table is hydrogen 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 expands to form ice. In other words DENSITY of ice is lower than that of liquid water and hence ice floats over water. Water is amphoteric in nature. It acts as an acid in presence of STRONG bases and as a base in presence of strong acids. `underset("Base"_1)(H_2O_((l)))+ underset("Acid"_2)(H_2S_((aq)))to underset("Acid"_1)(H_3O_((aq))^(+))+ underset("Base"_2)(HS_((aq))^(-))` `underset("Acid"_1)(H_2O_((l)))+ underset("Base"_2)(NH_(3(aq))) to underset("Acid"_2)(NH_(4(aq))^(+)) + underset("Base"_1)(OH_((aq))^(-))` Due to amphoteric character , water undergoes self ionisation as FOLLOWING : `underset("Acid"_1)(H_2O_((l)))+ underset("Base"_2)(H_2O_((aq)))hArr underset"(Conjugate acid)"underset("Acid"_2)(H_3O_((aq))^+)+ underset"(Conjugate acid)"underset("Base"_1)(OH_((aq))^(-))` This self ionisation of water is called auto protolysis.