Ramesh visited Delhi with his parents, where he saw buses and vehicles mostly running on CNG instead of petrol

Ramesh visited Delhi with his parents, where he saw buses and vehicles mostly running on CNG instead of petrol. He was surprised and wanted to know the reason behind it.
(i) How would you help Ramesh in reducing his confusion?
(ii) State two gases, which ,are emitted by burning of petroleum.
(iii) How these gases affect us?

(i) I would explain Ramesh that burning of petroleum causes more pollution than CNG (Compressed Natural Gas). Therefore, to control the level of air pollution, most vehicles including buses use CNG instead of petrol.
(ii) Oxides of nitrogen and sulphur (i.e. $N{{O}{2}}$ and
$S{{O}
{2}}$) gases are released into the atmosphere, by burning of petroleum.
(iii) Inhalation of these gases is dangerous. It may cause lung cancer, asthma, bronchitis, etc.
When these gases react with water in atmosphere, they become acidic and give rise to acid rain, which is harmful to the monuments and crops.