The correct spelling is dioxide.
Some example sentences are:
The correct spelling is "carbon dioxide" (CO2).
The correct spelling of the gaseous compound is "carbon dioxide" (CO2).
carbon dioxide.
The right spelling is atmosphere.
Yeah the right spelling is murderer
That is the correct spelling.
The correct spelling is Carbon Dioxide.
The correct spelling is entrust.
Begging is the correct spelling.
The correct spelling is woolen.
The correct spelling is valentine.
NO! The correct spelling is spinach.