(A) Why does a candle burn with a flame but coal does not?(B) How is the burning of fossil fuels the reason for submergence of coastal areas?

A) A candle burns with a flame because it undergoes a combustion process known as "complete combustion." A candle is typically made of a solid wax-like substance, such as paraffin wax, which contains hydrocarbon molecules. When the candle is lit, the heat of the flame melts the wax near the wick, which is then drawn up the wick via capillary action. Once the liquid wax reaches the flame's heat, it vaporizes and undergoes a chemical reaction with oxygen from the surrounding air.

The combustion process in a candle involves three essential components: fuel (wax), oxygen, and heat. The heat from the flame vaporizes the liquid wax, and the gaseous hydrocarbon molecules mix with oxygen to create a combustion reaction. This reaction releases energy in the form of heat and light, resulting in a visible flame. The combustion of hydrocarbons in the candle produces carbon dioxide (CO2) and water vapor (H2O) as byproducts.

On the other hand, coal does burn, but it does not produce a visible flame under normal conditions. Coal is a fossil fuel formed from the remains of plant material that lived millions of years ago. It consists mainly of carbon, with small amounts of hydrogen, sulfur, and other elements. When coal is burned, it undergoes a process called "incomplete combustion." Unlike a candle, coal does not contain the necessary components to sustain a visible flame.

During incomplete combustion, coal reacts with oxygen to release energy, but the reaction is not as efficient as in complete combustion. Factors such as the composition and structure of coal, the supply of oxygen, and the temperature at which it burns affect the combustion process. Incomplete combustion of coal produces carbon monoxide (CO), a toxic gas, along with carbon dioxide and other combustion byproducts. The lack of a visible flame when coal burns is due to the absence of certain volatile hydrocarbons found in candles and other fuels.

B) The burning of fossil fuels, including coal, oil, and natural gas, contributes to the submergence of coastal areas primarily through the process of climate change. When fossil fuels are burned, they release significant amounts of carbon dioxide (CO2) and other greenhouse gases into the atmosphere. These greenhouse gases act as a blanket, trapping heat from the sun and leading to an increase in global temperatures.

As global temperatures rise, the melting of polar ice caps and glaciers accelerates, resulting in a rise in sea levels. The increased volume of water contributes to the submergence or inundation of coastal areas, a phenomenon known as sea-level rise. The rate and extent of sea-level rise depend on various factors, including the amount of greenhouse gases emitted, the response of the climate system, and other local factors.

Coastal areas are particularly vulnerable to sea-level rise because they are low-lying and often densely populated. As the sea level rises, coastal erosion becomes more severe, and coastal flooding becomes more frequent and intense. Submergence of coastal areas can lead to the loss of land, displacement of communities, destruction of infrastructure, and ecological damage to coastal ecosystems.

It's important to note that while the burning of fossil fuels is a significant contributor to sea-level rise, other factors such as land subsidence and natural climate variability can also influence the submergence of coastal areas. However, the release of greenhouse gases from burning fossil fuels remains a primary driver of long-term global climate change, which in turn affects sea levels.