Geo + History 2nd Semester Notes

Ch.4: Rocks

Short Q/A

Q1: What is an element?

Ans: An element is the simplest form of matter.

Q2: What is meant by minerals?

Ans: Vital resources found in earth are called minerals.

Q3: Which organic elements are found in rocks?

Ans: Organic elements like oxygen, silicon, aluminum, iron, calcium, sodium,         potassium and magnesium are found in rocks.

Q4: What is rock?

Ans: Rock is a combination of two or more minerals.

Q5: Which things are found in rocks?

Ans: In some rocks crystals are found and in some rocks fossils of animals and     plants are found.

Q6: How many types of rocks are there?

Ans: There are three types of rocks.

Q7: Write names of types of rocks.

Ans: 1. Igneous Rocks

          2. Sedimentary Rocks

          3. Metamorphic Rocks

Q8: Which resources human beings use?

Ans: Human beings use resources i.e. coal, petroleum, salt, iron etc.

Q9: What is temperature of earth in centre?

Ans: Temperature of earth in centre is about 5000⁰ centigrade.

Q10: How magma is formed?

Ans: The minerals melt and thick igneous matter magma is formed.

Q11: What is lava?

Ans: The magma when comes on the surface of earth is called Lava.

Q12: What does word igneous mean?

Ans: The word igneous mean “fire”.

Q13: How many types of igneous rocks are there?

Ans: There are two types of igneous rocks.

Q14: Write names of types of igneous rocks.

Ans: 1. Intrusive Igneous Rocks

          2. Extrusive Igneous Rocks

Q15: What is meant by intrusive igneous rock?

Ans: When the molten matter solidifies deep inside the surface of the earth, the      rock thus formed is called Intrusive igneous rock.

Q16: Which rocks are intrusive igneous rocks?

Ans: Granite, diorite and gabbro are intrusive igneous rocks.

Q17: What is meant by extrusive igneous rocks?

Ans: When the molten matter comes on the surface of the earth and solidifies, the rock thus formed is called extrusive igneous rocks.

Q18: Which rocks are extrusive igneous rocks?

Ans: Basalt and obsidian are extrusive igneous rocks.

Q19: Why crystals are not found in extrusive igneous rocks?

Ans: The molten matter solidifies quickly that’s why crystals are not found.

Q20: Where extrusive igneous rocks are found in Pakistan?

Ans: In Pakistan these rocks are found in Hazara and Balochistan.

Q21: Which rocks are called primary rocks?

Ans: Igneous rocks are also primary rocks.

Q22: What is meant by sedimentary rocks?

Ans: The surface of earth weathered and eroded into sediments by solar heat,        rain, wind, river or glacier and deposited layer by layer. These layers fix   together firmly with the passage of time and a rock is formed which is    called sedimentary rock.

Q23: How many types of sedimentary rocks are there?

Ans: There are three types of sedimentary rocks.

Q24: Write the names of sedimentary rocks.

Ans: 1. Mechanically formed rocks

          2. Chemically formed rocks

          3. Organic rocks

Q25: What are mechanically formed rocks?

Ans: Wind, river and glacier erode the rock and deposit them in layered form. The rock formed by the layers is called Mechanically formed rock.

Q26: Which rocks are mechanically formed rocks?

Ans: sandstone, shale and conglomerate are mechanically formed rocks.

Q27: Where mechanically formed rocks are found in Pakistan?

Ans: In Pakistan mechanically formed are found in Northern areas and Potwar pleatue.

Q28: What are chemically formed rocks?

Ans: When water evaporates, it leaves behind layers behind layers of  salts. The    rocks formed by these layers are called chemically formed rocks.

Q29: Which rocks are chemically formed rocks?

Ans: Rock salt, gypsum and dolomite are chemically formed rocks.

Q30: Where chemically formed rocks are found in Pakistan?

Ans: In Pakistan these rocks are formed in salt range, Daud khel , D.G Khan and Dadu.

Q31: What is meant by organic rocks?

Ans: Organic rocks are formed by the fossils of animals and plants.

Q32: What is found in organic rocks?

Ans: Calcium and carbon are found in organic rocks.

Q33: What is meant by Calcareous rocks?

Ans: If fossils of animals are found in abundance then these rocks are called          calcareous rock.

Q34: Which rocks are calcareous rocks?

Ans: Limestone and corals are calcareous rocks.

Q35: Where calcareous rocks are found in Pakistan?

Ans: In Pakistan these rocks are found in Salt range and Hazara.

Q36: What is meant by carbonaceous rocks?

Ans: If fossils of plants are found in abundance then these rocks are called   carbonaceous rocks.

Q37: Which rock is carbonaceous rock?

Ans: Peat (raw coal) is carbonaceous rock.

Q38: What is meant by metamorphic rocks?

Ans: The rocks formed or buried under the surface of the earth are changed.          These changed rocks are called metamorphic rocks.

Q39: What are reasons of change?

Ans: There are two main reasons of this change.

(a) Temperature              (b) Pressure

Q40: How many types of metamorphic rocks are there?

Ans: There are two types of metamorphic rocks.

Q41: Write names of types of metamorphic rocks.

Ans: 1. Rocks formed by Thermal metamorphism

          2. Rocks formed by Regional metamorphism

Q42: How bricks are made?

Ans: Bricks are made by clay.

Q43: What is meant by thermal metamorphism?

Ans: The heat of magma, when moves inside the earth, passes near or over a rock, changes its composition and structure and a new rock is formed. This process is called thermal metamorphism.

Q44: What type of rock is marble?

Ans: Marble is metamorphic rock.

Q45: Write use of marble.

Ans: Marble is used in construction for durability and beauty.

Q46: Write use of limestone?

Ans: Limestone is used commonly for white wash.

Q47: Where marble is found in Pakistan?

Ans: Marble is found in area of Mullaghori (KPK) and Balochistan.

Q48: What is meant by regional metamorphism?

Ans: Earthquakes and mountain building forces cause a rock to sink inside the earth. This process is called regional metamorphism.

Q49: How slate is formed?

Ans: shale after being squeezed turns into slate.

Q50: Where metamorphic rocks are found in Pakistan?

Ans: In Pakistan these rocks are found in areas of Abbotabad and Kund.