Benzoic acid has ka =6.5× 10 ? 5 , and citric acid has ka =7.2× 10 ? 4. what is the stronger conjugate base?

The stronger conjugate base is, Citric acid.

Explanation :

The value of dissociation constant of Benzoic acid is higher than the citric acid. This means that the acid will readily dissociate and stronger will be the acid. Higher the value of dissociation constant of an acid weaker will be its conjugate base and the lower value of dissociation constant of an acid means that the stronger will be its conjugate base.

Therefore, the stronger conjugate base is Citric acid.

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.