NON-MEATALS, A . Carbon and its Various Forms

Total Questions: 40

11. Which of these is not an additional form of Carbon? [U.P.U.D.A./L.D.A. (Spl.) (Mains) 2010]

(a) Diamond
(b) Graphite
(c) Oxocarbon
(d) Fullerenes

Correct Answer: (c) Oxocarbon

Solution:Oxocarbon is an inorganic compound made up of carbon and oxygen only, and it is not an allotrope of carbon.

12. Pencil lead is — [Chhattisgarh P.C.S. (Pre) 2011, U.P.P.C.S. (Pre) 1994]

(a) Graphite
(b) Charcoal
(c) Lamp black
(d) Coal

Correct Answer: (a) Graphite

Solution:Graphite and Diamond both are allotropes of Carbon. Pencil cores are made of Graphite mixed with a clay binder which leaves grey or black marks that can be easily erased.

13. Lead Pencil contains — [U.P.P.C.S. (Mains) 2006, Uttarakhand U.D.A./L.D.A. (Pre) 2003]

(a) Lead
(b) Lead oxide
(c) Graphite
(d) Lead sulphide

Correct Answer: (c) Graphite

Solution:Graphite and Diamond both are allotropes of Carbon. Pencil cores are made of Graphite mixed with a clay binder which leaves grey or black marks that can be easily erased.

14. Consider the following statements: [I.A.S. (Pre) 2023]

Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
Carbon fibres once used cannot be recycled.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (a) 1 only

Solution:Carbon fibers can be defined as fibers with a carbon content of 90% or above. They are produced by thermal conversion of organic fibers with a lower carbon content such as polyacrylonitrile (PAN) containing several thousand filaments with diameter between 5 and 10 µm. The main advantage of carbon fibers compared to other fibers are the high tensile strength, high stiffness, low density, and a high chemical resistance. Carbon fibers are usually combined with other materials to form a composite. Carbon fiber-reinforced composite materials are used to make aircraft and spacecraft parts, racing car bodies, golf club shafts, bicycle frames, fishing rods, automobile springs, sailboat masts, and many other components where light weight and high strength are needed. Hence, statement 1 is correct. Carbon fiber (and carbon fiber composites) waste can be recycled using various mechanical, thermal, or chemical methods including virgin carbon fibre offcuts, carbon fibre- reinforced composites (CFRC), utilizing chemical reactions, size-reduction method using high-voltage, electrohydraulic and electrodynamic fragmentation, etc. Hence, statement 2 is not correct.

15. Third allotrope of Carbon was discovered by three scientists, who were awarded the Nobel Prize for Chemistry. Find out who was not on that team- [U.P.P.C.S. (Pre) 2009]

(a) H.W. Kroto
(b) Faimen
(c) R.E. Smalley
(d) R.F. Curl

Correct Answer: (b) Faimen

Solution:In 1996, Robert F. Curl (USA), Sir Herold W.Kroto (Britain) and Richard E. Smalley (USA) were awarded the Nobel Prize in Chemistry for the discovery of Fullerenes. It was the allotrope of Carbon in which the molecules of Carbon are fully condensed. Its molecular formula is C₆₀. It is named as Fullerenes after the name of the American architect and inventor Richard Buckminster Fuller.

16. Which one of the following pairs is not correctly matched? [U.P. P.C.S. (Mains) 2017]

(a) Dry ice: Solid carbon dioxide
(b) Sevin : Insecticide
(c) Teflon: Polymer containing fluorine
(d) Fullerene: Organic compound containing fluorine

Correct Answer: (d) Fullerene: Organic compound containing fluorine

Solution:Fullerene is an allotrope of carbon. Buckminsterfullerene is the cage-like molecule of fullerene which is composed of 60 carbon atoms (C₆₀) joined together by a single and double bond and to form a hollow sphere with 12 pentagonal and 20 hexagonal faces a design that resembles a Soccer ball. The C₆₀ molecule was named after the American Architect Fuller. Other pairs are correctly matched.

17. Buckminsterfullerene is — [U.P.P.C.S. (Mains) 2010]

(a) A form of carbon compound of clusters of 60 carbon atoms bonded together in a polyhedral structure composed of pentagons or hexagons
(b) A polymer of fluorine
(c) An isotope of carbon heavier than C¹⁴
(d) None of these

Correct Answer: (a) A form of carbon compound of clusters of 60 carbon atoms bonded together in a polyhedral structure composed of pentagons or hexagons

18. Which one of the following pairs is not correctly matched? [U.P.P.C.S. (Pre) 2001, 2003 U.P. Lower Sub. (Pre) 2003, U.P. Lower Sub. (Pre) 2002, U.P.U.D.A./L.D.A. (Pre) 2001]

(a) Fullerene: Organic compounds containing fluorine
(b) Dry Ice: Solid carbon dioxide
(c) Keratin: Protein found in the outer layer of human skin
(d) Mustard gas: Poisonous liquid used in chemical warfare

Correct Answer: (a) Fullerene: Organic compounds containing fluorine

Solution:

Dry Ice - We can simply say that dry ice is solid carbon dioxide (CO₂),. It is used as a cooling agent.

Mustard gas - It is used as a strong chemical weapon. This mortally chemical affects skin, leering eye, lungs and D.N.A. which affects the cells most. After 1-6 hours the symptoms seem to be visible.

Fullerene - Fullerene is an allotrope of the carbon family which fully carbon atoms are integrated. It is denoted by C₆₀.

Keratin - It is a family of fibrous structural proteins. Kama is the protein that protects epithelial cells from damage stress that has potential to fill the cell. It is the key structural material making up the outer layer of human skin.

19. Which one of the following pairs is not correctly matched? [U.P.P.C.S. (Pre) 2006]

(a) Dry ice : Solid carbon dioxide
(b) Mustard gas: Poisonous liquid used in chemical warfare
(c) Teflon: Polymer containing fluorine
(d) Fullerene: Organic compounds containing fluorine

Correct Answer: (d) Fullerene: Organic compounds containing fluorine