Consider the following statements : (i) Coal ash contains arsenic, lead and mercury. (ii) Coal-fired power plants release sulphur dioxide and oxides of nitrogen into the environment. (iii) High ash content is observed in Indian coal. Which of the statements given above is / are correct ?

- Statement (i) is correct. Coal ash, a byproduct of burning coal, is known to contain various toxic heavy metals, including arsenic, lead, and mercury, among others. These elements pose significant environmental and health risks if not properly managed. - Statement (ii) is correct. Coal contains sulfur and nitrogen compounds. When coal is burned in power plants, these compounds react with oxygen at high temperatures to produce sulphur dioxide (SO2) and oxides of nitrogen (NOx). These are major air pollutants that contribute to acid rain, respiratory problems, and photochemical smog. - Statement (iii) is correct. Indian coal is characterized by a relatively high ash content compared to coal found in many other major coal-producing countries. This high ash content leads to challenges in transportation, burning efficiency, and disposal of large quantities of coal ash.