Chemistry (Part-XI)

Total Questions: 50

21. Bee sting contains _______. [S.S.C. Online Graduate Level (T-I) 3.09.2016 (Shift-III) ]

(a) An acidic liquid
(b) a salt solution
(c) an alkaline liquid
(d) a corrosive liquid

Correct Answer: (a) An acidic liquid

Solution:A bee sting primarily contains a complex mixture of proteins and enzymes, the main active component being melittin, along with other compounds like histamine and phospholipase A2. This mixture is distinctly acidic, which is why baking soda (an alkali) is often used as a home remedy to neutralize the sting and alleviate pain.

22. Why does carbon tetrachloride have no dipole moment? [S.S.C. Online CHSL (T-I) 18.01.2017 (Shift-II) ]

(a) Because of same size of Carbon and Chlorine atoms.
(b) Because of regular tetrahedral structure.
(c) Because of planar structure.
(d) Because of similar electron affinities of carbon and Chlorine.

Correct Answer: (b) Because of regular tetrahedral structure.

Solution:Carbon tetrachloride (CCI₄) has no dipole moment due to its regular tetrahedral structure.

23. Compounds with exactly two double carbon carbon bonds are knows as _____ . [S.S.C. Online CPO SI (T-I) 10.11.2022 (Shift-II) ]

(a) Terpenes
(b) Dienes
(c) Trialkyne
(d) Dialkyne

Correct Answer: (b) Dienes

Solution:In organic chemistry, the prefixes indicate the number of functional groups.

"Di-" means two.
"-ene" refers to a carbon-carbon double bond.
Therefore, compounds with exactly two carbon-carbon double bonds are called dienes. Examples include 1,3-butadiene.

24. Activated Charcoal is used to remove colouring matter from pure substances by _____ . [S.S.C. Online Graduate Level (T-I) 29.08.2016 (Shift-III) ]

(a) Bleaching
(b) Oxidation
(c) Adsorption
(d) Reduction

Correct Answer: (c) Adsorption

Solution:Activated charcoal has the property of adsorption, due to which it separates the colored impurities found in pure substances by adsorbing on its surface. In this way, such substances come in completely pure form.

25. The most pure form of carbon among the options is- [S.S.C. Online Graduate Level (T-I) 29.08.2016 (Shift-I) ]

(a) Anthracite
(b) Lampblack
(c) Graphite
(d) Wood Charcoal

Correct Answer: (a) Anthracite

Solution:Anthracite is the hardest, brightest, and best form of coal. It has a carbon content of 90-95%. 55-80% carbon is found in bituminous, 40-55% in lignite, and less than 40% in peat coal.

26. Which is the highest hard coal of the below? [S.S.C. Online Constable GD 18.02.2019 (Shift-I) ]

(a) Bituminous
(b) Pete
(c) Lignite
(d) Anthracite

Correct Answer: (d) Anthracite

Solution:Coal is ranked based on its carbon content, moisture content, and heating value. The general progression from lowest to highest rank (and increasing hardness and carbon content) is: Peat → Lignite → Bituminous → Anthracite. Anthracite is known as "hard coal" due to its high carbon content and density, making it the hardest and highest-ranking coal type.

27. Highest percentage of carbon is found in which form of coal? [S.S.C. Online Graduate Level (T-I) 3.09.2016 (Shift-III), S.S.C. Online Graduate Level (T-I) 8.09.2016 (Shift-I) ]

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

Correct Answer: (a) Anthracite

Solution:Anthracite is the hardest, brightest, and best form of coal. It has a carbon content of 90-95%. 55-80% carbon is found in bituminous, 40-55% in lignite, and less than 40% in peat coal.

28. Peat coal has carbon and moisture content? [S.S.C. Online CGL (T-I) 13.12.2022 (Shift-1) ]

(a) High, Low
(b) Low, high
(c) High, High
(d) Low, Low

Correct Answer: (b) Low, high

Solution:Peat is the lowest rank of coal, forming from the decomposition of organic matter in swamps and bogs. It is an immature coal.

Carbon content: Being the earliest stage of coal formation, peat has a low carbon content (around 50-60%) compared to higher-rank coals.
Moisture content: Peat is very porous and retains a significant amount of water, hence it has a high moisture content.
This combination makes peat a less efficient fuel compared to other coals.

29. Burning of coal is an example of _____ . [S.S.C. Online CGL (T-I) 01.12.2022 (Shift-I) ]

(a) decomposition reaction
(b) double displacement reaction
(c) combination reaction
(d) displacement reaction

Correct Answer: (c) combination reaction

Solution:Burning of coal is primarily a combustion reaction, which is a type of combination reaction. In combustion, a substance (coal, primarily carbon) reacts with oxygen (from the air) to form a new compound (carbon dioxide) and release energy (heat and light).

C (s) + O₂ (g) → CO₂ (g)

This is a combination because two or more reactants combine to form a single product.

30. Unsaturated carbon compounds burn with a: [S.S.C. Online MTS (T-I) 12.10.2021 (Shift-I) ]

(a) white sooty flame
(b) orange sooty flame
(c) red sooty flame
(d) yellow sooty flame

Correct Answer: (d) yellow sooty flame

Solution:Unsaturated organic compounds burn with a yellow flame and a lot of black smoke, because they do not burn completely, but a large amount of unburned carbon is also released along with the smoke in the form of particulates, which produces yellow-black smoke.

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