11. The youngest supercontinent which is formed between 450 and 320 𝑀𝑀𝑀 and including most of the existing continent is termed as:

(a) Gondwana

(b) Laurentia

(c) Pangea

(d) Rodina

Answer: (c)

12. The property of some crystals displaying different colours when rotated in plane-polarized light under a microscope is known as:

(a) Play of colours

(b) Opalescence

(c) Iridescence

(d) Pleochroism

Answer: (d)

13. Cast iron when broken, the surface is studded with sharp and a jagged elevation is called:

(a) Conchoidal fracture

(b) Uneven fracture

(c) Hackly fracture

(d) Earthy fracture

Answer: (c)

14. In crystallography, the accurate measurement of interfacial angles is done by:

(a) Stereoscope

(b) Refractometer

(c) Optical goniometer

(d) Optical prism

Answer: (c)

15. The relief of a mineral directly depends upon the difference between the Refractive Index (RI) of the mineral and RI of the enclosing cement of the thin section, which is always:

(a) 1.540

(b) 1.730

(c) 1.820

(d) 1.910

Answer: (a)

16. The mineral serpentine is an example of:

(a) Nesosilicates group

(b) Sorosilicates group

(c) Phyllosilicates group

(d) Tektosilicates group

Answer: (c)

17. Cellular deposits of calcium carbonates derived from water charged with calcareous matter in solution is called:

(a) Satin spar

(b) Calc tufa

(c) Thinolite

(d) Aphrite

Answer: (b)

18. Magma that generates and segregates at greater depth has a greater possibility to be erupted on the surface because of:

(a) The driving force of over head pressure

(b) Higher concentration of lighter element

(c) Presence of volatile content

(d) High pressure of rising gases

Answer: (a)

19. In a binary system, due to the crystallization of magmatic melt at eutectic point, the texture formed is:

(a) Porphyritic texture

(b) Ophitic texture

(c) Intergranular texture

(d) Graphic texture

Answer: (d)

20. The magma of considerable viscosity injected into stratified rocks does not spread very far, but tends to heap itself up about the orifice of irruption, which resulted in the formation of:

(a) Phacolith

(b) Laccolith

(c) Batholith

(d) Dykes

Answer: (b)