अम्लीय वर्षा तब होती है जब पर्यावरण में ____ उत्सर्जित होता है।

When the pH of rainwater is less than ______, it is called acid rain.

Burning of plastics, especially Polyvinyl Chloride (PVC), releases which of the following highly toxic substances into the atmosphere?

Which of the following specific chemical compounds is formed when sulphur dioxide reacts with atmospheric moisture during the sulphur cycle?