the following answer originates from my knowledge or is an edit of an other users knowledge. i have underlined words were not hyperlinks and have been done so for the public's better understanding.
In our solar system Mercury is the smallest of the eight planets, and is the only one not to have an atmosphere. This may be due to:-
A planet's atmosphere doesn't have strength.
Jupiter and all the gas giants.
Not all planets have wind. Wind is caused by the movement of gases in an atmosphere, so planets without a significant atmosphere, like Mercury or the Moon, would not have wind. Additionally, the intensity and frequency of wind can vary greatly depending on factors such as atmospheric composition, temperature gradients, and surface features.
Negative, not only do the inner planets have atmospheres, but the outer planets also have atmospheres. The masses of the outer planets are great, enough easily to hold an atmosphere. In fact it's Mercury, an inner planet, that has almost no atmosphere. True, Mercury has a less mass and the closeness to the sun make it impossible to hold on a atmosphere. As matter in fact, Mars had a atmosphere, but the solar wind had almost eaten all the atmosphere that Mars had.
An atmosphere is a layer of gas that is part of a planet, and usually surrounds it solid part, if there is a solid part. so for each planet, there is one and only one plant in its atmosphere. The earth is the only planet in the Earth's atmosphere; Mars is the only plant in the Martian atmosphere; etc.,
air and gasses and for some no atmosphere
they all have different gasses in there atmosphere
Atmosphere.
A planet's atmosphere doesn't have strength.
Yes, all planets have atmosphere but to my knowledge mars' is not breathable.
No many like Mars have no atmosphere at all.
The thinnest atmosphere belongs to planet Mercury . . . it may have no atmosphere, at all.
because its cold
Gas particles (atoms, molecules) composing the atmosphere of a planet have a mass, therefore they are trapped by the gravitational field of the planet. This is not only true for giant planets but applies to all planets with atmosphere.
Jupiter and all the gas giants.
The outer planets does not have enough oxygen to sustain life, or they don't have an atmosphere at all.
The inner planets Mercury, Venus, Earth, Mars are are all relatively small, they are all rocky, they all have a relatively thin atmosphere.