Mars

 Can we breathe in Mars ?

The atmosphere on Mars is mostly made of carbon dioxide. It is also 100 times thinner than the Earth's atmosphere, so even if it did have a similar composition to the air here, humans would be unable to breathe it to survive.

Because Earth is tectonically active, old crust continually melts into the mantle and forms new crust at plate boundaries, recycling water and other molecules back into the atmosphere through volcanism. Mars however, is mostly tectonically inactive, and so the " drying" of the surface, once it occurs, is permanent.\

Can we plant trees on Mars?

Growing a tree on Mars will surely fail with time. The Martian soil lacks nutrients for soil growth and the weather is too cold to grow a tree...... .