MBOSE Class 12 Question Paper 2025 for Geology

Meghalaya Board of School Education

QUESTION
PAPERS

Total No. of Printed Pages—8
HS/XII/Sc/Gl/25

2025

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 of any six of the
following : 1×6=6

(a) Sedimentary rocks are
(i) primary rocks
(ii) secondary rocks
(iii) Both (i) and (ii)
(iv) None of the above

/232 [ P.T.O.

( 2 )

(b) Disintegration is associated with

(i) physical weathering

(ii) chemical weathering

(iii) organic weathering

(c) Rain-prints are formed on the top surface of loose
sediments due to

(i) the effect of solar heat

(ii) movement of organisms on the surface of loose
and soft sediments

(iii) impacts of drops of rainwater

(d) Brachiopods are characterised by the presence of a
test made up of

(i) two equal valves

(ii) two unequal valves

(iii) one valve

(e) The bottommost beds of the Jaintia series is known
as

(i) Kopili stage

(ii) Sylhet stage

(iii) Therria stage

HS/XII/Sc/Gl/25/232 [ Contd.

( 3 )

(f) Deposits of clay, silts and alluvial materials are often
utilised for the construction of
(i) earth dams
(ii) masonry dams
(iii) cofferdams

(g) Bauxite is an ore of
(i) iron
(ii) zinc
(iii) aluminium
(h) Organisms capable of swimming against a current
are said to be
(i) planktonic
(ii) nektonic
(iii) benthonic

2. State whether the following statements are ‘True’
or ‘False’ (any six) : 1×6=6

(a) The rocks of sedimentary origin occur essentially in
the form of layers/beds.

(b) Index fossils are not useful in establishing the correct
age of the rock beds in which they occur.

(c) Lamellibranchs with two adductor muscles are
known as Monomyaria.

(d) Gastropods exhibit dextral coiling of the shell.

(e) A number of individual beds of more or less similar
characteristics together constitute a formation.

HS/XII/Sc/Gl/25/232 [ P.T.O.

( 4 )

(f) Magmatic concentration includes dissemination,
segregation and injection.

(g) Acid rain can contaminate lakes and streams.

(h) Rains promote landslide.

3. Fill in the blanks (any six) : 1×6=6

(a) The remains of plants and animals preserved by
nature within the rocks are known as _____.

(b) _____ are very often developed due to drying under
sub-aerial conditions in fine grained sediments.

(c) The teeth and sockets together form the _____.

(d) Earthquake waves are also called _____.

(e) Coal is a _____ deposit.

(f) Coal of North-East India is of _____ tertiary coal.

(g) Galena is an ore of _____.

(h) The Jaintia Group is overlained by the _____ group.

4. Express each of the following lines in 1 (one) word (any
five) : 1×5=5

(a) The process of formation of mineral deposits due to
invasion of magmatic emanations into the country
rocks

(b) Water that is present beneath the earth’s surface in
rock and soil pore-spaces and in the fractures of rock
formations

HS/XII/Sc/Gl/25/232 [ Contd.

( 5 )

(c) A violent and abrupt shaking of the ground

(d) An ore of copper

(e) Rocks that essentially occur in the form of layers or
beds

(f) Undulations produced on the surface of sediments

5. Match Column—A with Column—B and write the
corresponding numbers : 1×6=6

Column—A Column—B
(a) Tremors (i) Anthracite
(b) Brown coal (ii) Tenor
(c) Iron (iii) Bauxite
(d) Metal content of an ore (iv) Lamination
(e) Supergene enrichment (v) Earthquake
(f) Thin layers (vi) Foliation
(vii) Hematite
(viii) Lignite
(ix) Exogenetic process

6. Write on the following in 1 (one) or 2 (two) line(s) (any six) :
1×6=6

(a) Current bedding

(b) Conditions favourable for preservation of fossils

(c) Index fossils

HS/XII/Sc/Gl/25/232 [ P.T.O.

( 6 )

(d) Correlation

(e) Dentition

(f) Uses of mica

(g) Permeability

(h) Open-cast mining

( PART : B—DESCRIPTIVE )
( Marks : 35 )

Answer five questions, selecting one from each Group

GROUP—A
( Sedimentology )

7. Explain how disintegration differs from decomposition.
What are rudaceous rocks? Describe how lithification of
rocks takes place. 2+2+3=7

8. Write short notes on any two of the following : 3½×2=7

(a) Nodules and concretions

(b) Mechanical structures of sedimentary rocks

(c) Non-clastic rocks

9. Describe the textures of sedimentary rocks on the basis of
grain size and; roundness and sorting. 7

HS/XII/Sc/Gl/25/232 [ Contd.

( 7 )

GROUP—B
( Paleontology )

10. Outline the morphology of a typical gastropod shell with a
neat labelled sketch. 6+1=7

11. Write short notes on any two of the following : 3½×2=7

(a) Types of suture in cephalopods

(b) Glossopteris

(c) Morphology of a brachiopod

12. Define a fossil. Explain briefly the different modes of
preservation of fossils. 1+6=7

GROUP—C
( Stratigraphy )

13. Outline the lithostratigraphy of Paleozoic of Spiti in
tabular form. 7

14. Write short notes on any two of the following : 3½×2=7

(a) Upper Vindhyan

(b) Tipam Group

(c) Jaintia Group

15. Write briefly on the Precambrian of Dharwar Supergroup
of Karnataka. 7

HS/XII/Sc/Gl/25/232 [ P.T.O.

( 8 )

GROUP—D
( Energy and Mineral Resources )

16. Explain the formation of economic minerals by magmatic
processes. 7

17. Write short notes on any two of the following : 3½×2=7

(a) Mode of occurrence of petroleum

(b) Distribution of radioactive minerals in India

(c) Types of coal

18. Give an account on the origin and distribution of bauxite
in India. 7

GROUP—E
( Engineering Geology, Groundwater, Environment
and Disaster Studies )

19. Describe the geological considerations required for the
construction of dams. 7

20. Write short notes on any two of the following : 3½×2=7

(a) Aquifer

(b) Mitigation of landslides

(c) Effects of earthquake

21. What is open-cast mining? Describe the impact of
open-cast mining on the environment. 1+6=7

HHH

HS/XII/Sc/Gl/25/232 K25—??

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