Rockets burn different fuels and so will produce different pollutants. The late space shuttle's main engine used hydrogen as a fuel so the only direct product was water, though of course if the exhaust produced is hot enough it can cause the formation of nitrogen oxides if it passes through air. Other engines burn hydrazine which can react in different ways but typically mainly produces nitrogen and either hydrogen or water. The soyuz rockets in use today (2016) burn hydrocarbon mixtures which are chemicallly similar to petrol (gasoline) and so produce the same pollutants: carbon dioxide and monoxide, nitrogen oxides. Sulfur compounds are removed from hydrocarbons for this use, so sulfur dioxide is unlikely. Inefficient combustion and side reactions can also make particulates. It is worth remembering that the number of rocket launches is so small that the pollution they produce is insignificant compared to aircraft.
When the engine is cold or when it is misfiring.
a lot
yes
Yes. There is no "green" way to get a shuttle into space yet. Just take a look at any of the videos of shuttle launches that have ever been made and you'll see that there's quite a lot of pollution.
Planes.
Because they let out fume from the burning fuel.
Rocket fuel can have environmental impacts such as the release of greenhouse gases, depletion of the ozone layer from chemicals like chlorine, and contamination of soil and water from spills or leaks. The combustion of rocket fuel can also produce air pollution and contribute to climate change.
A space shuttle launch generates significant pollution, primarily due to the combustion of rocket propellants. The solid rocket boosters release large amounts of chlorine gas and particulate matter, while the liquid fuel produces carbon dioxide, water vapor, and other gases that contribute to atmospheric pollution. Estimates suggest that a single shuttle launch can emit several hundred tons of pollutants, affecting air quality and contributing to climate change. However, the overall impact of space launches is relatively small compared to other industrial activities.
because CNG does not cause of any pollution and does not emit carbon.
No, nuclear power maintains environment non pollution as it does emit green house gases and do not contribute to global warming and environment pollution.
Mobile pollution is caused from the exhausts from cars. The exhausts emit carbon monoxide (CO) which causes respiratory disorders such as asthma and bronchitis in people.
They emit horrific greenhouse gases like carbon dioxide & methane that pollute the air.