Based on it physical properties is a colloid a homogeneous mixture or heterogenous mixture? how does it differ from a solution?

Colloid is homogeneous mixture.

In solution the particle size is less than one nm. While particles in colloid are larger than solution particles.  When light pass through solution it can not scatter the light.

Explanation:

Colloidal:

Colloid consist of the particles having size between 1 - 1000 nm i.e, 0.001- 1μm.  

The particles in colloid can not be seen through naked eye.

It is homogeneous.

We can not separate the colloidal through the filtration. The pore size of filter paper is 2μm. However it can be separated through the ultra filtration. In ultra filtration the pore size is reduced by soaking the filter paper in gelatin and then in formaldehyde. This is only in case of when solid colloidal is present, if colloid is liquid , there is no solid particles present and ultra filtration can not be used in this case.

In solution the particle size is less than one nm. While particles in colloid are larger than solution particles.  When light pass through solution it can not scatter the light.

explanation:

since this is put under health, i would define "ethical (medical) behavior" the way the oath for doctors is recited.   "first do no harm."

but the term in general means when given a choice between right and wrong, we should always choose right. if we do, then we are practicing ethical behavior.