Which of the following expands to fill the container it is in but can be compressed to a smaller volume when pressure is applied?
a. solid iron
b. liquid bromine
c. neon gas
d. sugar crystals

C. neon gas

Explanation:  There are three states of matter:

A. Solid iron: The molecules in solid are very tightly packed as inter molecular forces are very high. There is very less space between the particles and thus the molecules can not be compressed. They have fixed shape and volume.

B. liquid bromine: The molecules in liquid are less tightly packed as inter molecular forces are not very high. There is less space between the particles and thus the molecules can not be compressed. They have fixed volume and take the shape of the container.

C. neon gas : The molecules in gas are very less tightly packed as inter molecular forces are very low. There is large vacant space between the particles and thus the molecules can be compressed. They neither have fixed volume nor a fixed shape.They occupy complete volume of the container in which it is put.

D. sugar crystals: The molecules in solid are very tightly packed as inter molecular forces are very high. There is very less space between the particles and thus the molecules can not be compressed. They have fixed shape and volume.

it is the most commonly accepted one

it's c (engineer's do their work with mechanical stuff not on any living being)