Add spaces: Itsfrontlegcompartmentscanstorepensandaccessories,whileitiseasytomovearoundandneatlyfoldsflatforstorage.

Answer: Its front leg compartments can store pens and accessories, while it is easy to move around and neatly folds flat for storage.

Add spaces: Acertainmassnumberbelongstoacertainkindofsubstance,thuscannotbetwodifferentsubstanceshavethesamemassnumber.

Answer: A certain mass number belongs to a certain kind of substance, thus can not be two different substances have the same mass number.

Add spaces: Goldchalicewithenamelledpainting.

Answer:
Gold chalice with enamelled painting.