When styrofoam gets dissolved by the acetone, the gas from the foaming agent used to make styrofoam is released. The styrofoam then condenses into a smaller and denser solid

a) Branch LDPE has reduced mechanical strength, so it cannot withstand the required strength
b) the molecules of HDPE must be arranged in a manner that gives it higher strength. Linear arrangement has a larger surface, and so has a larger induced intermolecular force

No it does not happen to the piece of paper. When the piece of plastic is stretched, the molecules will be arranged to become parallel to the direction of the pull. This would be an irreversible change and the plastic will snap. Paper is made of cellulose in which the molecules are more rigidly held in place because of stronger intermolecular forces

a) ease of implantation, non-toxic, stable in body, high corrosive resistance
b) Polymethylmethacrylate (PMMA), silicon acrylate
Desirable properties: non-toxic, transparent, permeability to oxygen, comfortable, high durability
c) “hard”contact lenses are made of PMMA and “soft”contact lenses are made of silicon acrylate. Silicon acrylate is more flexible and is more fitting to the eye. “Hard”lenses are not as comfortable to wear as “soft”lenses and they may fall out more frequently. “soft” lenses easily absorb soap and lotion from our hands, causing eye irritation.