NON-MEATALS, A . Carbon and its Various Forms

Total Questions: 40

21. Which of the following do not contain carbon? [U.P. Lower Sub. (Mains) 2013]

(a) Diamond
(b) Graphite
(c) Coal
(d) Sand

Correct Answer: (d) Sand

Solution:Carbon is capable of forming many allotropes due to is valency. The well-known forms of Carbon included Diamond and Graphite. Coal is a sedimentary organic rock that contains a lot of Carbon (between about 40% to 90% carbon by weight). Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. does not contain Carbon. Sand is primarily composed of silicon dioxide (

SiO₂

), also known as silica.

22. Which of these consists carbon? [U.P.P.C.S. (Pre) 1993]

(a) Lignite
(b) Tin
(c) Silver
(d) Iron

Correct Answer: (a) Lignite

Solution:Coal minerals are divided mainly into four types based on the percentage of carbon:

Lignite: 25-35%
Sub-bituminous: 35-45%
Bituminous: 45-85%
Anthracite: More than 85%.

23. Which one of the following types of coal contains a higher percentage of carbon than the rest? [U.P.U.D.A./L.D.A. (Pre) 2001, I.A.S. (Pre) 1999]

(a) Bituminous coal
(b) Lignite
(c) Peat
(d) Anthracite

Correct Answer: (d) Anthracite

Solution:Coal minerals are divided mainly into four types based on the percentage of carbon:

Lignite: 25-35%
Sub-bituminous: 35-45%
Bituminous: 45-85%
Anthracite: More than 85%.

24. The highest amount of carbon is in — [U.P.P.C.S. (Mains) 2014]

(a) Pig Iron
(b) Wrought Iron
(c) Steel
(d) Alloy Steel

Correct Answer: (a) Pig Iron

Solution:Explanation:

Pig iron has a very high carbon content (3.5-4.5%).
Wrought iron has a very low carbon content (less than 0.08%).
Steel contains about 0.2% to 1.5% carbon.
Alloy steel has 0.1% to 1% carbon.

25. Which of the following is not in the form of crystal? [M.P.P.C.S. (Pre) 1996]

(a) Diamond
(b) Quartz
(c) Sulphur
(d) Graphite

Correct Answer: (c) Sulphur

Solution:Salt, Sugar, Diamond, Quartz, Ice, Graphite etc. are in the form of crystal but Sulphur is not. It is a multivalent non- metallic chemical element. Sulphur: Can exist in various forms. While it does have crystalline allotropes (like rhombic and monoclinic sulfur), it also commonly exists in an amorphous (non-crystalline) form called plastic sulfur or colloidal sulfur.

26. Consider the following statements: [I.A.S. (Pre) 1999]

Glass can be etched or scratched by —

Diamond
Hydrofluoric Acid
Aqua regia
Concentrated Sulphuric Acid

Which of these statements are correct?

(a) 1 and 4
(b) 2 and 3
(c) 1 and 2
(d) 2 and 4

Correct Answer: (c) 1 and 2

Solution:Diamonds are used for grinding, cutting, drilling and polishing. It is used as an abrasive. Very small pieces of diamonds are embedded into grinding wheels, saw blades or drill bits. The hardest element diamond is used to cut or scratch the Glass. Hydrofluoric (HF) acid is one of the strongest inorganic acids which is used mainly for industrial purposes (eg. glass etching, metal cleaning, electronics manufacturing).

27. For the selling of diamonds, the unit of weight is carat. One carat is equal to — [U.P.P.C.S. (Mains) 2013]

(a) 100 mg
(b) 200 mg
(c) 300 mg
(d) 400 mg

Correct Answer: (b) 200 mg

Solution:The carat (ct) is a unit of mass equal to 200 mg and is used for measuring gemstones and pearls. One metric carat is internationally defined as exactly 200 milligrams (0.2 grams).

28. Graphene is frequently in the news recently. What is its importance? [I.A.S. (Pre) 2012]

It is a two-dimensional material and has good electrical conductivity.
It is one of the thinnest but strongest materials tested so far.
It is entirely made of silicon and has high optical transparency.
It can be used as 'conducting electrodes' required for touchscreens, LCDs, and organic LEDs.

Which of the statement(s) given above is/are correct?

(a) 1 and 2
(b) 3 and 4
(c) 1, 2, and 4
(d) 1, 2, 3, and 4

Correct Answer: (c) 1, 2, and 4

Solution:Graphene is an allotrope of Carbon with the thickness of a molecule which shows a remarkable quality. The two scientists of Manchester University-Andre Geim and Kostya Novoselov discovered it in 2004. The both were awarded 'Nobel Prize' in 2010 for the discovery of Graphene. They extracted Graphene from a piece of Graphite. Graphene is a bi-dimensional element and due to this quality, controlling electricity is easier in it than a tri-dimensional element. Graphene is not only very thin but also strongest among all the materials tested so far. It is almost transparent, despite

29. Which one of the following materials is strongest? [U.P.P.C.S. (Mains) 2015]

(a) German Silver
(b) Brass
(c) Steel
(d) Graphene

Correct Answer: (d) Graphene

Solution:

When comparing strength, particularly tensile strength (resistance to breaking under tension) on a per-unit-mass basis, graphene is outstanding:

German Silver, Brass, and Steel are all alloys, and while strong in their own right, they are significantly less strong than graphene on a relative basis.
Graphene is renowned for being one of the strongest materials known to humankind, approximately 200 times stronger than structural steel by weight.

30. Consider the following statements and select the correct answer from the codes given below: [U.P.U.D.A./L.D.A. (Pre) 2001]

Water becomes harder due to the presence of Calcium Sulphate and is not usable.
Diamond is harder than copper and iron.
Oxygen is the main component of air.
Nitrogen is used in the manufacture of vegetable ghee.

Code:

(a) 1 and 2
(b) 3 and 4
(c) 1 and 3
(d) 2 and 4

Correct Answer: (a) 1 and 2

Solution:Hard water has high mineral content caused by the dissolved Magnesium Sulphate or Calcium Sulphate. This is due to the permanent hardness of sulphate salts which do not decompose on heating.

Diamond is the hardest substance.

By volume, dry air contains about 78% of Nitrogen.

Vanaspati ghee, a fully or partially hydrogenated vegetable cooking oil is often used as a cheaper substitute for ghee. Hydrogen gas is used in the production of vegetable ghee, not the nitrogen.

So, only statement 1 and 2 are correct.

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