What is the principle gas in the vensusian atmosphere and also a minor component of the atmospheres of earth and mars?

Answer 1

There is no gas that fits this description. Carbon dioxide is about 95% of the

Venusian atmosphere, but it's also about 95% of the atmosphere on Mars.

Of course it's also a minor component of the atmosphere of the Earth too.

Answer 2

The principle gas in the Venusian atmosphere is carbon dioxide (CO2). It is also a minor component of the atmospheres of Earth and Mars. On Venus, however, carbon dioxide makes up over 96% of the atmosphere, creating a strong greenhouse effect.