MBOSE Class 11 Question Paper 2023 for Geology

Total No. of Printed Pages ––9
HS/XI/Sc/Gl/23

2023

GEOLOGY

( THEORY )

Full Marks : 70

Time : 3 hours

The figures in the margin indicate full marks for the questions

General Instructions:

(i) Write all the answers in the Answer Script.

(ii) Attempt Part–A Objective Questions serially.

(iii) Attempt all parts of a question together at one place.

( PART : A–OBJECTIVE )

( Marks : 35 )

1. Choose and write the correct answer (any 6) : 1  6=6
(a) The combined effect of weathering and erosion
is called
(i) aggradation
(ii) denudation
(iii) decomposition.

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(8) (3)

11. Writes short notes on any two of the followings: (f) The first mineral to crystallize out from a basaltic
3½ x 2 = 7 magma is
(a) Cleavage and fracture of minerals. (i) quartz
(b) Isotropism and anisotropism (ii) K-feldspar
(c) Symmetry elements of crystals (iii) olivine

12. Define polarization of light. Explain the construction
and working of a Nicol prism. 1+6=7 (g) Acid magmas are rich in

(i) Si, Na, K

(ii) Ca, Mg, Fe
GROUP – C
(iii) Si, Fe, Mn.
( Structural Geology and Geotectonics )

13. Write brief notes on the types of faults with neat
(h) With increasing metamorphism, the grain size
sketches. 7
of minerals

(i) increase
14. Write short notes on any two of the following: 3½ x 2 = 7
(ii) decrease
(a) Strike and Dip.
(iii) remain constant.
(b) Elastic, plastic and brittle deformations.

(c) Joints.
2. State ‘True’ or ‘False’ (any six): 1  6=6

(a) P-and S-waves travel through solids, liquids and
15. What are folds. Write briefly on any four elements of
gases alike.
folds. Distinguish between (a) antiform and anticline
(b) plunging and non-plunging folds. 1+2+2+2=7 (b) Waterfalls are features due to stream erosion.

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(5) (6)

(e) The crystallization of plagioclase with albite and 5. Match Column A with Column B and write the
anorthite as end members is an example of ______ corresponding numbers : 1  6=6
reaction series.
Column A Column B
(f) Two or more joints parallel to each other with a
regular spacing is called a joint ______. (a) Hexagonal (i) Graphic granite

(g) When no fault block moves up or down, but slip (b) Convection currents (ii) low amplitude
past each other in a horizontal manner, then the (c) Continuous reaction (iii) metamorphism
fault must be a _______ fault.
(d) Intergrowth (iv) hkl
(h) A fine-grained dark colored low grade (e) Aureole (v) Solid solution
metamorphic rock is ______.
(f) P-wave (vi) high amplitude
(vii) asthenosphere
4. Express the following in one word (any five) : 1  5=5 (viii) volcanic rock

(a) Younger rocks towards the top and older rocks (ix) hkil
towards the bottom in a rock succession.
6. Answer in 1 (one) or 2 (two) lines (any six) : 1  6=6
(b) Country rock fragments in intruding
magma. (a) Bed load

(c) Magma splitting into parts with different (b) Lustre
composition as a result of cooling. (c) Isoclinal fold

(d) A group of metamorphic minerals that form under (d) Gneiss
the same set of physical and chemical conditions. (e) Directed pressure

(e) Rock below a fault plane. (f) Cryptocrystalline texture
(g) Boss
(f) Difference between the maximum and minimum
refractive index of a mineral. (h) Inequigranular texture

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(4) (7)

(c) Curved fractures in minerals showing concentric ( PART : B–DESCRIPTIVE )
lines are called “uneven” fractures.
( Marks : 35 )
(d) Displacement along fault is called slip.
Answer five questions, selecting one from each Group
(e) When an oceanic plate collides with a continental
plate, the oceanic plate moves over the continental GROUP – A
plate. ( General Geology )

(f) Cavities on top of volcanic igneous rocks give rise
to ‘trachytic texture’. 7. Outline how earthquake waves help to X-ray the
earth’s interior. 7
(g) Igneous mineral grains without any faces are said
to be ‘anhedral’. 8. Write short notes on any two of the following : 3½ x 2 = 7
(a) Uniformitarianism
(h) Large well-shaped crystals in metamorphic rocks
are called porphyroblasts. (b) Products of volcanoes

(c) Types of stream erosion.

3. Fill in the blanks (any six) : 1  6=6
9. Distinguish weathering from erosion. List the agents
(a) A mass of minute particles of gases, dusts and of weathering. Explain briefly any two chemical and
icy particles that ultimately formed the solar any two physical processes of weathering.
system is called the solar_______.
1+2+2+2=7
(b) The upper solid and rigid part of the earth GROUP – B
is called the ______. ( Crystallography and Mineralogy )

(c) The symmetrical intergrowth of two or more
crystals is called _______. 10. List the symmetry elements of the Normal class of the
Isometric system. Draw a clinographic sketch of the
(d) A ______ is a dome shaped igneous rock body with Isometric system. List the forms developed. Name a
mineral crystallizing in the Isometric system.
a flat base and domed top.
1½ + 1 + 4 +½ = 7

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(2) (9)

(b) Eocene time is immediately followed by GROUP – D

(i) Oligocene ( Igneous Petrology )

(ii) Paleocene
16. Illustrate the process of crystallization of a bi-
(iii) Miocene. component magma. 7

17. Write short notes on any two of the following : 3½ x 2 = 7
(c) Under crossed-Nicols, the colour of a mineral,
(a) Assimilation
except at extinction, is called
(b) Discontinuous reaction series of Bowen.
(i) anisotropism
(c) Filter pressing.
(ii) interference colour
18. Write brief notes on the common textures of igneous
(iii) pleochroism. rocks with neat sketches, based only on mutual
relationship of grains. 7

(d) An example of a brittle structure is GROUP – E
(i) fold ( Metamorphic Petrology )
(ii) fault
19. Write notes on the types of metamorphism. 7
(iii) tectonic plate.
20. Write short notes on any two of the following :
3½ x 2 = 7
(e) The inclination of a line in a rock is measured (a) Riecke’s principle
by (b) Grades of metamorphism and index minerals.
(i) trend (c) Metamorphic facies.

(ii) rake 21. Write brief notes on any seven metamorphic texture/
structure with neat sketches. 7
(iii) dip.
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