CG Board Class 9 Science Chapter 16 Solutions: Coal, Petroleum and Petrochemicals (कोयला, पेट्रोलियम एवं पेट्रोरसायन) – 2026-27

What are fossil fuels?

Fuels formed from the dead remains of plants and animals buried under the earth’s crust millions of years ago under high pressure, high temperature, and absence of oxygen are called fossil fuels. Examples include coal, petroleum, and natural gas.

How is coal formed?

About 28 to 36 crore years ago, during the Carboniferous period, dense forests and plant remains got buried under layers of soil. Over millions of years, in the absence of oxygen and under immense pressure and heat deep inside the earth, the buried plant material underwent slow chemical decomposition to form peat, which eventually transformed into lignite, bitumen, and anthracite coal.

Which type of coal has maximum sulfur content?

Bitumen (Bituminous coal) contains the maximum amount of sulfur compared to other types of coal.

What is fractional distillation?

Fractional distillation is a separation technique used to separate a mixture of two or more miscible liquids whose boiling points are very close to each other, using a fractionating column.

Why is fractional distillation of petroleum necessary? What type of gases are obtained in the upper part of the fractionating column?

• Necessity: Petroleum is a complex mixture of many hydrocarbons having boiling points very close to each other. Simple distillation cannot separate these components, making fractional distillation necessary to extract individual useful components like petrol, kerosene, diesel, and petroleum gas.
• Upper Part Fraction: Lower boiling point components rise to the topmost cooler region of the fractionating column. Petroleum gas (consisting mainly of butane and propane) is obtained at the upper part (around 65°C).

Why does petroleum not have a chemical formula?

Petroleum is not a single pure chemical compound; rather, it is a variable mixture of numerous different solid, liquid, and gaseous hydrocarbons along with small amounts of other organic compounds. Since its composition varies from one source to another, it does not possess a fixed chemical formula.

What do we mean by the recycling of plastics?

The process of collecting discarded or waste plastic materials, sorting them according to their SPI identification codes (1 to 7), melting, and processing them to form new useful products is called plastic recycling.

What is combustion? Explain.

The chemical process in which a substance reacts with oxygen to produce heat and light is called combustion. It is an exothermic reaction. For example, complete combustion of coal produces carbon dioxide and heat energy

C + O₂ → CO₂ + Heat

(i) Coal is produced from the remains of:**

• (a) Plants
• (b) Animals
• (c) Both plants and animals
• (d) None of these

(ii) The conditions necessary for formation of fossil fuels are:

• (a) High temperature
• (b) High pressure
• (c) Absence of oxygen
• (d) All of the above

(iii) Which type of coal has maximum carbon content:

• (a) Peat
• (b) Lignite
• (c) Bitumen
• (d) Anthracite

(iv) What is the identification code found on objects made of PVC?

• (a) 1
• (b) 2
• (c) 3
• (d) 4

(i) Coal and petroleum are ……………….. fuels.**

(ii) During formation of coal, ……………….. is formed in the first stage and ……………….. is formed in the last stage.

(iii) The least carbon content is found in ……………….. type of coal.

(iv) Fractional distillation is carried out when there is a very small difference in the ……………….. of liquids in the mixture.

(v) Petroleum is a combination of two words: ……………….. and ………………..

• Fossil fuels (coal, petroleum, and natural gas) were formed from the dead remains of organisms that lived 28 to 36 crore years ago during the Carboniferous period.
• Formation of Coal: Buried remains of dense swamp vegetation got covered by soil layers. Over millions of years, high temperature, extreme pressure, and absence of oxygen converted them into peat, lignite, bitumen, and anthracite coal.
• Formation of Petroleum: Dead marine microscopic organisms (planktons) settled at the ocean floor and got covered under sand and clay layers. Under anaerobic conditions, high pressure, and temperature, they transformed into petroleum and natural gas over millions of years.

Coal is categorized into four main types based on its carbon content

1. Peat: The initial stage of coal formation from dead plants. It contains 25 to 35% carbon and high moisture content; mostly used as basic fuel.
2. Lignite: Also known as brown coal, containing 35 to 45% carbon. It is primarily used in thermal power stations to generate electricity.
3. Bitumen (Bituminous Coal): The most abundant and widely used type of coal. It contains 45 to 85% carbon and relatively higher sulfur content. Used in thermal plants, steel manufacturing (as coke), cement, paper, and textile industries.
4. Anthracite: The highest quality hard coal containing more than 85% carbon. It burns cleanly with a hot flame, producing very little smoke and ash; used as household and industrial fuel.

Excessive burning of fossil fuels leads to severe environmental problems

1. Greenhouse Effect and Global Warming: Combustion releases large quantities of CO₂ gas. Unabsorbed CO₂ accumulates in the atmosphere, trapping heat and causing global warming.
2. Air Pollution and Toxic Gas Emission: Incomplete combustion releases poisonous Carbon Monoxide (CO), which binds rapidly with blood hemoglobin, reducing oxygen transport and causing health hazards or death.
3. Acid Rain: Fossil fuels contain sulfur and nitrogen, which burn to form oxides (SO₂, NO_x). These dissolve in rainwater forming acids that cause acid rain, damaging soil, vegetation, aquatic life, and buildings.
4. Fly Ash Pollution: Burning coal produces fine mineral particles called fly ash, which pollute the air and cause respiratory diseases like silicosis in humans.

Limited Reserves:** Fossil fuels require millions of years to form naturally, but current known reserves are depleting rapidly and may last for only about 100 years at the present consumption rate.

• Conservation Measures:

1. Drive vehicles at uniform, moderate speeds and turn off the engine at traffic signals (PCRA tips).
2. Prefer cleaner alternative fuels like Compressed Natural Gas (CNG) over petrol/diesel.
3. Use energy-efficient mining techniques to prevent resource wastage during extraction.
4. Promote renewable energy sources (solar, wind, hydro) and recycle plastics in moderation.

• Products & Uses / :