Correct answer
Carbon dioxide.
The main gases emitted by a vehicle are carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), unburnt hydrocarbons (HC) and lead compounds. Carbon dioxide is not toxic at normal concentrations; evidence of this is that the lungs expel carbon dioxide when we breathe out. Plants are the only organisms capable of converting carbon dioxide (CO2) into oxygen.
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Iron oxide.
Magnesium oxide.
Carbon dioxide.
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