Answer:
Matter exists in three forms in nature:
- Solid: in a solid, the particles of the substance are tightly bonded to each other, and they cannot move freely, but they can only vibrate around their fixed position. Solids have a definite volume and a definite shape.
- Liquid: in a liquid, the particles of the substance can slide past each other, however there are still intermolecular forces acting between them and keeping them close to each other. Liquids have a definite volume, but not a definite shape.
- Gas: in a gas, the particles of the substance can move freely, as there are no intermolecular forces acting between them. Gases have no definite volume and no definite shape.
In this problem therefore, the substances that are solids are:
Rock: yes
Rubber band: yes
Milk: no (liquid)
Feather: yes
Cloth: yes
Baby powder: yes
Sugar: yes
Foam-rubber ball: yes
Styrofoam: yes
Air: no (gas)
Flour: yes
Dust: yes
Cooking oil: no (liquid)
Sponge: yes
Iron nail: yes
Ice: yes
Wood: yes
Soil: yes
Melting wax: no (liquid)
Salt: yes
Cotton ball: yes
