Exp) Option a is the correct answer.

Artificial rainfall, more commonly known as cloud seeding, is a technique used to induce or enhance precipitation from clouds. It is increasingly being explored in India as a way to combat severe air pollution, particularly in cities like Delhi where high levels of particulate matter and smog make air quality dangerous.

The process of cloud seeding involves dispersing certain substances into the atmosphere that serve as cloud condensation or ice nuclei. These particles encourage water vapor in the atmosphere to condense into water droplets or ice crystals. When these droplets become heavy enough, they fall as rain.

One of the most commonly used chemicals for this purpose is silver iodide (AgI). This compound has a crystalline structure similar to ice, which makes it effective in stimulating the formation of ice crystals within cold clouds. Once seeded, the silver iodide helps initiate the process of condensation and precipitation.

In addition to silver iodide, potassium iodide (KI) is also used. It can serve a similar function by acting as a condensation nucleus, though it is less commonly used than silver iodide. Together, these chemicals can enhance the cloud’s ability to produce rainfall, helping to clear out pollutants from the air by washing them down to the ground.

This method has been considered by Indian authorities during peak pollution seasons as a way to create artificial rain and thereby reduce the concentration of pollutants in the lower atmosphere.

Source: https://www.hindustantimes.com/india-news/what-is-cloud-seeding-all-about-artificial-rain-used-when-aqi-is-high-101732095089202.html#:~:text=is%20cloud%20seeding?-,Cloud%2Dseeding%20is%20a%20technique%20used%20to%20modify%20weather%20by,ice%20nucleation%20and%20subsequent%20precipitation. ; https://www.timesnownews.com/mirror-now/in-focus/article/what-is-artificial-rain-will-it-solve-delhis-air-pollution-woes/317375 https://www.business-standard.com/india-news/combating-air-pollution-with-artificial-rain-cloud-seeding-explained-123111000854_1.html