Download App

Coal and Petroleum — Science STD 8 — Question

Gujarat BoardEnglish MediumSTD 8ScienceCoal and Petroleum4 Marks
Question
Describe how, fossil fuels were formed.
✓

Answer

The fossil fuel such as coal is formed from the remains of dead vegetation. Earth had dense forests in low lying wetland areas about $300$ million years ago. Due to natural processes, like flooding, these forests got buried under the soil. Due to soil deposition over these dead plants, they were compressed. The temperature also increased as they sank deeper and deeper. Under high pressure and high temperature, dead plants got slowly converted to coal. As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonisation. Since it was formed from the remains of vegetation, coal is also called a fossil fuel. The fossil fuel such as petroleum is formed from the dead animals under the sea. As these organisms died, their bodies settled at the bottom of the sea. They got covered with layers of sand and clay. Over millions of years, in the absence of air, with high temperature and high pressure, these the dead organisms were transformed into petroleum and natural gas.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "questions in details [4 marks ]" from Coal and Petroleum→Coal and Petroleum — all question types→Science STD 8 question papers→Gujarat Board STD 8 question papers→Gujarat Board question paper generator→

Similar questions

Match the substances in Column A with their applications given in Column $B.$
 
Column A(Substance)
 
Column B(Application)
$(a)$
Oxygen
$(i)$
For making crackers
$(b)$
Copper
$(ii)$
For disinfecting water
$(c)$
Sulphur
$(iii)$
All living beings inhale during breathing
$(d)$
Iron
$(iv)$
For making electric wires
$(e)$
Chlorine
$(v)$
For making rails
→
What is the cause of friction? Explain with the help of a labelled diagram.
→
What can be done to retain our ‘green wealth’ for the future generations?
→
Define frictional force (or friction).
→
$X$ and $Y$ are the two types of animals. The animals like $X$ undergo external fertilization whereas animals like $Y$ undergo internal fertilization. The animals like $X$ lay eggs from which baby animals are hatched. On the other hand, in animals like $Y$, the young one develops inside the uterus of mother which then gives birth to the baby.
$1.$ What is the general name of animals like $X$?
$2.$ Give two examples of animals like $X$?
$3.$ What is the general name of animals like $Y$?
$4.$ Write the names if two animals like $Y$.
→
Saniya claims to her friend Vinita that “Antibiotics can cure any infection, so we don’t need to worry about diseases.” What question(s) can Vinita ask her to help Saniya understand that her statement is incorrect?
→
What is meant by the terms ‘internal fertilization and ‘external fertilization’? Explain with example.
→
Give an example to show that friction depends on the force with which the two surfaces are pressed together.
→
What do you mean by weeding? Why the process of weeding necessary? Name the methods applied for weeding.
→
The fossil fuel $P$ is formed under the earth by the decomposition of vegetable matter lying under water by the action of anaerobic bacteria. The major component of fuel $P$ is $Q$. The fossil fuel $P$ is used as a source of gas $R$ needed to manufacture nitrogenous fertilisers. When $P$ is filled in metal cylinders and used as a fuel in motor vehicles, it is called $S$. What are $P, Q, R$ and $S?$
→