Questions

Caverns are openings in the ground. Some famous caverns in the United States are Mammoth Cave, Carlsbad Caverns, Wind Cave, and Luray Caverns.

When rainwater trickles down through the soil, it carries carbon dioxide from the air with it. This turns acidic as it moves through the soil, joining with carbon from decaying plants. This acidic rainwater then eats away at, or erodes, the rock under the ground, forming a cave or cavern. For this process to occur, the rock must be the right type; limestone, dolomite, and gypsum are common.

The First and Last Indian viceroys of India is C. Raj Gopalachari. 

Chakravarti Rajagopalachari, informally called Rajaji or C.R., was an Indian politician, independence activist, lawyer, writer, historian and statesman. Rajagopalachari was the last Governor-General of India, as India soon became a Republic in 1950.

Magnesium is dissolved in seawater at a concentration of about 1,000 parts per million and is the only metal directly extracted from seawater.