Why is it necessary to use models to study submicroscopic objects such as atoms and molecules? a. these objects do not exist in the real world. b. these objects are too far away to observe. c. these objects are too small to see. d. these objects can only be described mathematically.

The answer is C. These objects are too small to see.

The answer is: C. These objects are too small to see.

For example, ball and stick model gives informations about bond lenght and space filling model gives information about space occupied by atoms.

In chemistry, the ball-and-stick model is a molecular model of a chemical substance which is to display both the three-dimensional position of the atoms and the bonds between them. The atoms are represented by spheres, connected by rods which represent the bonds. Every ball represent one atom in one molecule and they have different colors for different atoms (for example, carbon is black, hydrogen is white, nitrogen is blue).  

There also other models: skeletal models, polyhedral models, composite models, computer-based models.  

i do not get it   at all

he uptake of drugs from the intestine is often strongly influenced by diffusion. for example, consider a water-insoluble steroid for treating inflammation that is solubilized in aggregates of detergent molecules, called micelles. these micelles, aggregates of 80 soap molecules, have a molecular weight of 24,000, a diameter of 2.6 nm, and a charge of -27. the positively charge ions (counterions) in this system are na".