The Brownian motion is due to

• Temperature fluctuation within the liquid phase
• Attraction and repulsion between charges on the colloidal particles
• Impact of molecules of the dispersion medium on the colloidal particles
• Convection currents

• reaches a constant limiting value
• goes on increasing with pressure
• goes on decreasing with pressure
• increases first and decreases later with pressure

• Refraction of the blue light by the impurities in sea water.
• Reflection of blue sky by sea water.
• Scattering of blue light by water molecules.
• Absorption of other colours except blue colour by water molecules.

• dispersion effect 
• Reflection
• Transmission
• Scattering