Chemistry (Part-XIII)

11. What is the major constituent of Gobar gas? [S.S.C. Online C.P.O.S.I. (T-I) 3.07.2017 (Shift-II) ]

(a) Propane
(b) Butane
(c) Methane
(d) Ethylene

Correct Answer: (c) Methane

Solution:Gobar gas is produced by the decomposition of biomass such as dung, excreta, urine, etc. For its construction, filling the above substances in a tank made in a big pit and letting them rot in a closed environment, due to which Gobar gas, whose main component is methane, starts to be generated in a few days.

12. Which of the following is the primary component of quartz? [S.S.C. Online M.T.S. (T-I) 14.10.2021 (Shift-III) ]

(a) Zinc
(b) Aluminium
(c) Silica
(d) Iron

Correct Answer: (c) Silica

Solution:Quartz is a widely found mineral on Earth, the main component of which is silicon dioxide (SiO₂). Quartz is piezoelectric in nature, that is, when pressure is applied to its crystal, positive and negative charges are generated at its ends. Properly cut plates of quartz are used for frequency control in radio, television, and other electronic communication equipment and in crystal-controlled clocks.

13. Which of the following is the other name for 'Marsh Gas'? [S.S.C. Online CGL (T-I) 24.08.2021 (Shift-II) ]

(a) Methane
(b) Propane
(c) Butane
(d) Ethane

Correct Answer: (a) Methane

Solution:Marsh gas is also called methane gas. Methane is an organic compound, the primary constituent of natural gas. It is a flammable gas and starts coming out of coal mines, due to which there is a possibility of explosion in these mines.

14. The colour of an emerald is generally ______ . [S.S.C. Online Graduate Level (T-I) 18.08.2021 (Shift-I) ]

(a) yellow
(b) blue
(c) green
(d) red

Correct Answer: (c) green

Solution:Emerald is a precious gemstone usually of green color. It is a member of the beryl mineral family. Its chemical formula is [Be₃Al₂Si₆O₁₈]. That is, emerald is a combination of beryllium, aluminium, silicon, and oxygen.

15. Which of the following is NOT used to make toothpaste? [S.S.C. Online CGL (T-I) 13.08.2021 (Shift-II) ]

(a) Aluminium Oxide
(b) Galena
(c) Silica
(d) Limestone

Correct Answer: (b) Galena

Solution:Aluminium oxide, silica, and limestone (CaCO₃) are used to make toothpaste, but galena (PbS) or lead sulfide is not used in it. It is a toxic substance for the body.

16. Topaz is a ______ of fluorine and aluminium. [S.S.C. Online Graduate Level (T-I) 16.08.2021 (Shift-III) ]

(a) carbonate
(b) phosphate
(c) silicate
(d) sulphate

Correct Answer: (c) silicate

Solution:Topaz is a silicate mineral containing fluorine and aluminium (Al). Its chemical formula is Al₂SiO₄ (F₂OH)₂. It is used as a gemstone in jewelry.

17. Methane is a colourless, odourless, non-toxic but flammable gas. What is its common name? [S.S.C. Online Graduate Level (T-I) 4.03.2020 (Shift-II) ]

(a) Marsh gas
(b) Blue vitriol
(c) Heating gas
(d) Laughing gas

Correct Answer: (a) Marsh gas

Solution:Methane (CH₄) is a saturated hydrocarbon gas, which is the major constituent of natural gas. It is also called marsh gas because it also comes out of marshy land. Explosions occur only due to the leakage of methane in coal mines.

18. Which of the following is not a Halon gas? [S.S.C. Online CHSL (T-I) 29.01.2017 (Shift-II) ]

(a) Methane
(b) Carbon Tetra Chloride
(c) Jodomethane
(d) Bromomethane

Correct Answer: (a) Methane

Solution:Halons are halogenated hydrocarbons, specifically a group of chemicals that contain carbon, fluorine, and at least one other halogen (chlorine, bromine, or iodine). They were widely used as fire suppressants but are now largely phased out due to their ozone-depleting potential.
Methane ( $C H_{4}$ ): Methane is a simple alkane, a hydrocarbon, and does not contain any halogens. Therefore, it is not a Halon

19. Which of the following are isomers? [S.S.C. Online MTS (T-I) 14.10.2017 (Shift-II) ]

(a) Ethane and Propane
(b) Methane and Methene
(c) Propane and Propene
(d) Butane and Isobutane

Correct Answer: (d) Butane and Isobutane

Solution:Butane and isobutene are structural isomers. Their chemical properties are different from each other. Butane has four carbon atoms bonded in a straight chain, whereas isobutene has a branched structure.

20. Which of the following is an aldehyde? [S.S.C. Online Graduate Level (T-I) 4.06.2019 (Shift-II) ]

(a) Propine
(b) Propanone
(c) Propanal
(d) Propanol

Correct Answer: (c) Propanal

Solution:An aldehyde is an organic compound containing a formyl group (

R - C H O

), where a carbonyl group (C=O) is bonded to a hydrogen atom and an alkyl group (or another hydrogen in the case of formaldehyde).