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7 Gaseous World!

Fill in the blanks with the help of your knowledge of gases (Refer cluebox).

Gases are everywhere. The (i) is an envelope of gases that surrounds
the Earth. In (ii) , atoms and
molecules are compact and close together. (iii)
have atoms that are spread out
a little more. The molecules in gases are really
spread out, full of energy, and constantly moving

around in random ways.

Gases can fill a container of any (iv)
or shape. It doesn’t matter how big the container
is. The molecules spread out to fill the whole space
equally. Think about a balloon. No matter what shape you make the balloon, it will be
evenly filled with the gas (v) . Even if you make a balloon animal, the
molecules are spread equally throughout the entire shape.

Gas or Vapor?

(vi) and gas mean the same thing. The word vapor is used to describe
gases that are usually liquids at room temperature. Some examples of these types of
(vi) include water (H O) and Mercury (Hg). They are called vapors when
2
they are in a (viii) phase. You have probably heard the term “water
vapor”, which means water in a gaseous state. Compounds such as carbon dioxide
(CO ) are usually gases at room temperature.
2
Compressing Gases

Gases hold huge amounts of (ix) and their molecules spread out as
much as possible. When compared to solids or liquids, the molecules spread out in
gaseous systems can be (x) with very little effort. Combinations of
increased (xi) and decreased (xii) force gases into

containers that we use every day.
You might have compressed air in a spray bottle or felt the carbon dioxide rush out of

a can of soda. Those are both examples of gases forced into a smaller space at greater
pressure. As soon as the gas is introduced to an environment with a (xiii)
pressure, it rushes out of the container. The gas molecules move from an area of high
pressure to one of low pressure.

(a) energy, (b) compressed, (c) pressure, (d) volume, (e) lower, (f) Vapor,
(g) liquids, (h) gaseous, (i) helium, (j) size, (k) atmosphere, (l)solids,

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