Some polymers are elastic because they are made of
a. carbon.
c. sugar and alcohol.
b. phosphate ladders.
d. cross-linked chains.

Option (d) is the correct answer.

Explanation:

A polymer is defined as a substance which contains repeating units of monomers. Basically, a polymer is a long chain of monomer units as 'poly' means many and "mer" means units.

Hence, a polymer contains many units. Some polymers are long linear chains and some are cross-linked polymers.

A polymer is elastic in nature because it contains chains which are cross-linked. These chains have the ability to adjust themselves according to the force or stress applied on them.

As this cross-linkage is covalent in nature therefore, it makes sure that when stress is removed then the elastomer will return to its original shape.

Thus, we can conclude that some polymers are elastic because they are made of cross-linked chains.

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.

idk what the question is about