Railway Science (Chemistry-Carbon And its Compound)

Total Questions: 71

11. Which of the following properties is not shown by carbon? [RRC Group D 26/08/2022 (Morning)]

Correct Answer: (a) Metallic properties
Solution:

A property by which a carbon atom can bond with any number of other carbon atoms to form straight chains, branched chains and rings of various sizes. Covalency - It occurs when The valency of carbon is four, and four covalent bonds can be formed by one carbon atom.
Allotropy - The property of an element in which the elements exist in more than one physical form having similar chemical properties but different physical properties. Important allotropes of carbon include diamond, graphite, and fullerene.

12. Which of the following types of coal has the highest carbon content? [RRC Group D 26/08/2022 (Evening)]

Correct Answer: (d) Anthracite
Solution:

Anthracite - Best quality hard coal (90 to 98% carbon). Bituminous - most widely available and used coal (60 to 85% carbon). Lignite - Brown and Lower grade coal (55 to 70% carbon). Peat - Contains 30 to 60% carbon and more impurities.

13. If carbon will form C 4- , then the number of electrons and protons in the carbon ion will be ______ and _______ respectively. [RRC Group D 30/08/2022 (Morning)]

Correct Answer: (c) 10 ; 6
Solution:

The atomic number of the carbon is 6. So, there are 6 electrons as well as 6 protons in a carbon atom. But here the given carbon is a negative ion with -4 charge on it. This means it has received 4 extra electrons. So, the total number of electrons becomes 10, while the total number of protons is the same i.e. 6.

14. The catenation property shown by carbon refers to which of the following properties? [RRC Group D 01/09/2022 (Morning)]

Correct Answer: (a) Self - combining capacity to form a long chain of atoms
Solution:

The self-linking property of an atom to other atoms of the same element through sharing electrons to form chains and rings. Carbon has a unique nature in that it is able to catenate and form millions of organic compounds. Examples of elements showing catenation: Carbon, Silicon, Boron,etc.

15. Which of the following elements shows catenation properties similar to that of carbon? [RRC Group D 01/09/2022 (Afternoon)]

Correct Answer: (b) Si
Solution:

(symbol - Si and atomic number - 14). Catenation is the self-linking property of an atom i.e. ability of atoms to link with one another through covalent bonds. Silicon is widely used in semiconductors. Use – to make microchips. Duralumin - An aluminum alloy and is primarily used in the manufacture of lightweight structures such as aircraft components.

16. Consider the below statements and identify the correct answer. [RRC Group D 02 /09/2022 (Morning)]

Statement I: Most carbon compounds are good conductors of electricity. Statement II: The force of attraction between the molecules of carbon compounds is not very strong.

Correct Answer: (a) Statement II is correct, and Statement I is incorrect.
Solution:

Carbon compounds form covalent bonds hence they have a weak force of attraction. Carbon has 4 valence electrons which have the ability to form 4 covalent bonds. Therefore, there is no extra electron present in carbon compounds to conduct electricity. They have no free electrons. So most of the carbon compounds do not conduct electricity.

17. Why do organic carbon compounds have lower melting points than ionic compounds? [RRC Group D 13/09/2022 (Morning)]

Correct Answer: (b) Weak force of attraction between molecules
Solution:

Made up of ions that form charged particles when an atom (or group of atoms) gains or loses electrons. Structure - Electrostatic attraction between the positive and negative ions. Carbon compounds - Molecules that contain a carbon atom. The attractive forces between molecules are weak, it does not take much energy to disrupt. Organic molecules have low melting and boiling points. Organic compounds burn in the presence of oxygen to form carbon dioxide and water.

18. Naphthalene balls are prepared from_________. [RRC Group D 13/09/2022 (Evening)]

Correct Answer: (d) coal tar
Solution:

Naphthalene is found in cigarette smoke, car exhaust, and smoke from forest fires. It was first registered as a pesticide in the United States in 1948. Uses - as an insecticide and pest repellent. Coke is carbon-based and has a high calorific value. Uses - as a fuel in steel foundries' blast furnaces. Petroleum is a naturally occurring liquid found beneath the earth's surface that can be refined into fuel. The 3 main kinds of petroleum are crude oil, natural gas, and bitumen. Coal gas is a mixture of methane (CH₄), hydrogen (H₂) and carbon monoxide (CO), formed by the destructive distillation of coal.

19. The bond generally NOT found in carbon compounds is: [RRC Group D 14/09/2022 (Morning)]

Correct Answer: (c) ionic bond
Solution:

Ionic bond is the transfer of valence electrons between atoms. Carbon compound - A compound that contains Carbon atoms. Types of carbon compound: Saturated Carbon Compounds - Carbon atoms that are linked together by single bonds only. Example - Ethane (C₂H₆). Unsaturated Carbon Compounds - Carbon atoms that are linked together by double or triple bonds. Ethene (C₂H₄) , Benzene (C₆H₆) , Propene (C₃ H₆) , Butadiene (C₄ H₆).

20. Which of the following elements can form both a double bond and a single bond with a carbon atom? [RRC Group D 15/09/2022 (Morning)]

Correct Answer: (d) O
Solution:

(Oxygen, 8) is a nonmetal (gas) and has six valence electrons. It can form a double bond with carbon, as in the molecule carbon dioxide (CO₂), where each oxygen atom shares two electrons with the carbon atom, resulting in a double bond. It can form a single bond with the carbon in the molecule carbon monoxide (CO).