Why is entropy of ice less than that of water?

Assertion : Ice cube floats on water. Reason : Density of ice is less than that of water.

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

The molar enthalpy of vaporisation of acetone is less than that of water. Why ?

At a particular temperature why is the vapour pressure of acetone less than that of ether?

Why is the electron gain enthalpy of O or F less than that of S or Cl?

The absolute entropy of a liquid is less than of the solid.

The Lewis acid strength of BF_3 is less than that of BCl_3 Why?

Why is ice less dense than water and what kind of attractive forces must be overcome to melt ice ?

Why is the bond angle of water less than the bond angle of CH_(4) ?

Entropy of the solutions is higher than that of pure liquid . Why?