Yes hydrogen is a colorless odorless gas, it is the the first chemical element on the periodic table and the most reactive.
It is a colorless, toxic gas but it is responsible for the foul smell of rotten eggs and other things.
yes
A Hydrogen atom is one proton, one electron. The ion has lost the 1 electron, but it is still the same element, if that's what you mean. Protons are used to define what the element is.
They can't react.
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