Dry ice is frozen carbon dioxide. A solid dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation as it breaks down, it turns directly into carbon dioxide gas rather than a liquid. The super-cold temperature and the sublimation feature make dry ice great for refrigeration.

An element is a substance that cannot be broken down into two or more simple substances by chemical methods involving the application of heat, light, or electrical energy. Hence, Neon is a chemical element; it has symbol Ne and atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of air.

When water freezes, water molecules form a solid structure maintaining hydrogen bonding. Ice is less dense than liquid water because the orientation of hydrogen bonds causes molecules push farther apart by lowering the density.

Air is a mixture, not compound. There are multiple elements present in air but they do not react with each other to form a singular substance that can be called "air". Air can be broken down basically into 78% nitrogen, 22% oxygen, and residual other gases and substance.

Benzene is an organic chemical compound with the molecule. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal ring with one hydrogen atom attached to each other. As it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.

A chemical change is a change of materials to form into another, different materials with different properties and one or more new substances are formed. Rusting of iron is a chemical change because a new substance iron oxide is formed. The presence of oxygen and water is essential for rusting. Rusting of iron is a continuous process that slowly eats up the iron objects and makes them useless.

Water is known to exist in three different states; as a solid, liquid or gas. 

Moisture, snow, and rain are all made of up of some form of water. Moisture in the air is comprised of vapor, a snowflake is an aggregate of many ice crystals, and rain is just liquid water.

The basic unit of matter is atom, around 100 picometers, which reacts with chemical.

Atomic nucleus consists of electrically positive protons and electrically neutral neutrons. These two forces are also called strong force.

The combination of two nuclides is called isotones if they have same neutron number-N, but different proton number-Z. Example: Boron-12, Carbon-13.