What is true about ice?

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?

The $O-H$ bond length in $H_2O$ in the gas phase is: (in $pm$)

Zeolite is hydrated sodium aluminium silicate. When treated with hard water,the sodium ions in zeolite are exchanged with

What is meant by 'demineralised' water and how can it be obtained?

If the same mass of liquid water and a piece of ice is taken,why is the density of ice less than that of liquid water?