Explanation:

• Smog is a combination of smoke and fog (smoky fog) caused by the burning of large amounts of coal, vehicular emission, and industrial fumes.
• It usually contains particulates like smoke, sulfur dioxide, nitrogen dioxide, and other components.
• At least two distinct types of smog are recognized: Sulfurous smog and Photochemical Smog.
• The Sulfurous smog or “London smog,” results from a high concentration of sulfur oxides in the air caused by the use of sulfur-bearing fossil fuels, particularly coal (Coal was the mains source of power in London during the 19th century, the effects of which started becoming evident in the early twentieth century).
• The Photochemical smog or “Los Angeles smog” It is sometimes called Oxidizing smog as it contains high concentrations of oxidizing agents like Ozone, HNO3 whereas Classical Smog is called Reducing as it contains high concentrations of sulphur dioxide, which is a reducing agent.Hence, statement 1 is correct.
• It occurs most prominently in urban areas with anthropogenic air pollutants, including ozone, nitric acid, and organic compounds.
• Such pollutants are the large numbers of automobiles.
• These are "Secondary pollutants" which occur as a result of the reaction between primary pollutants.Hence, statement 2 is correct.
• [Primary pollutants: It is any pollutant emitted directly from a source] It is caused by the action of solar ultraviolet radiation on polluted air.Hence, statement 3 is not correct.