Acombination of bonded atoms attached to a carbon skeleton is called

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Why do you suppose the structural polysaccharide cellulose does not contain branches? why do you suppose the structural polysaccharide cellulose does not contain branches? branches in the molecule would generate side chains that would almost certainly make it difficult to pack the cellulose molecules into globules, thereby decreasing the flexibility and strength of the globules. branches in the molecule would generate side chains that would almost certainly make it difficult to pack the cellulose molecules into microfibrils, thereby increasing the rigidity and strength of the microfibrils. branches in the molecule would generate side chains that would almost certainly make it difficult to pack the cellulose molecules into globules, thereby increasing the flexibility and strength of the globules. branches in the molecule would generate side chains that would almost certainly make it difficult to pack the cellulose molecules into microfibrils, thereby decreasing the rigidity and strength of the microfibrils.

Which type of orbits are found in the principal energy level n = 2 a - s b - s, f c - s, d d - s, p e - s, p, d