Precipitation of rain and snow is only a change of state and no new substance is formed.

The correct answer is option C - Conversion of water into steam.

Explanation:
A chemical reaction is a process in which one or more substances are converted into different substances with new chemical properties. It involves the breaking and formation of chemical bonds.

a) Burning of paper:
The burning of paper involves a chemical reaction. The heat from the flame breaks down the cellulose in the paper, leading to the formation of carbon dioxide, water vapor, and ash. This process is known as combustion.

b) Digestion of food:
The digestion of food is also a chemical reaction. It begins in the mouth with the breakdown of carbohydrates into simpler sugars by the enzyme amylase. In the stomach and small intestine, proteins are broken down into amino acids, and fats are broken down into fatty acids and glycerol. These reactions involve the action of various enzymes and acids.

c) Conversion of water into steam:
Water evaporating to form steam is not considered a chemical reaction. It is a physical process known as evaporation. Evaporation occurs when the water molecules gain enough energy from the surroundings to break free from the liquid phase and enter the gas phase as water vapor. No new substances are formed, and the chemical composition of water remains the same.

d) Burning of coal:
The burning of coal involves a chemical reaction known as combustion. When coal is burned, it reacts with oxygen in the air to produce carbon dioxide, water vapor, and heat. This process releases energy and is commonly used for power generation.

In summary, the conversion of water into steam is not a chemical reaction. It is a physical process called evaporation. The other options mentioned in the question involve chemical reactions.

Option c is the correct answer reason pls search on the internet and