Chemistry

111. Bronze is an alloy of copper and

Bronze is an alloy of copper and

[amp_mcq option1=”nickel” option2=”iron” option3=”tin” option4=”aluminium” correct=”option3″]

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UPSC CAPF – 2017
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Bronze is an alloy of copper and tin.
– An alloy is a mixture of metals, or a mixture of a metal and another element.
– Bronze is historically one of the most important alloys, known for its hardness and durability compared to pure copper.
– Typically, bronze consists primarily of copper, usually with tin as the main additive. The amount of tin varies but is commonly between 5% and 20%.
Brass is another common copper alloy, primarily consisting of copper and zinc. Other elements like aluminum, manganese, phosphorus, or silicon may be added to bronze to achieve specific properties, but tin is the defining secondary element for classical bronze.

112. Leakage of which one of the following gases had caused Bhopal Gas Trag

Leakage of which one of the following gases had caused Bhopal Gas Tragedy in the year 1984 ?

[amp_mcq option1=”Methyl isocyanate” option2=”Hexamethylene diisocyanate” option3=”Isophorone diisocyanate” option4=”Isothiocyanate” correct=”option1″]

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UPSC CAPF – 2017
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The leakage of Methyl Isocyanate (MIC) gas caused the Bhopal Gas Tragedy in 1984.
The Bhopal Gas Tragedy occurred on the night of December 2–3, 1984, at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh. A leak of methyl isocyanate gas and other chemicals resulted in thousands of deaths and long-term health issues for many more.
Methyl Isocyanate (MIC) is a highly toxic organic compound used in the production of pesticides. It is a volatile, flammable liquid. The incident is considered one of the world’s worst industrial disasters.

113. Which one of the following artificial sweeteners is modified sugar ?

Which one of the following artificial sweeteners is modified sugar ?

[amp_mcq option1=”Aspartame” option2=”Saccharin” option3=”Sucralose” option4=”Alitame” correct=”option3″]

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UPSC CAPF – 2017
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Sucralose is an artificial sweetener that is a modified sugar.
Sucralose is derived from sucrose (table sugar) by replacing three hydrogen-oxygen groups on the sucrose molecule with chlorine atoms. This chemical modification makes it about 320 to 1,000 times sweeter than sugar but indigestible by the body, hence providing virtually no calories.
Aspartame is a methyl ester of a dipeptide of the amino acids aspartic acid and phenylalanine. Saccharin is a synthetic sweetener with a bitter aftertaste, discovered in 1879. Alitame is a high-potency dipeptide-based artificial sweetener. Unlike sucralose, these are not chemically modified forms of sucrose.

114. Which one of the following statements is not correct ?

Which one of the following statements is not correct ?

[amp_mcq option1=”Graphite is a non-metal” option2=”Graphite is an allotrope of carbon” option3=”Graphite is a conductor of electricity” option4=”Graphite has a tetrahedral structure” correct=”option4″]

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UPSC CAPF – 2016
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Statement D is incorrect. Graphite has a layered structure where carbon atoms are arranged in hexagonal rings. Each carbon atom is covalently bonded to three other carbon atoms within the same layer. These layers are held together by weak van der Waals forces. A tetrahedral structure is characteristic of diamond, another allotrope of carbon, where each carbon atom is bonded to four other carbon atoms in a three-dimensional network.
Distinguishing between the structures of different allotropes of carbon like graphite and diamond is fundamental in chemistry and materials science.
Statement A is correct: Graphite is an allotrope of carbon, which is a non-metal element.
Statement B is correct: Graphite is one of the naturally occurring allotropes of carbon.
Statement C is correct: Graphite is a good conductor of electricity due to the presence of delocalized electrons within its layered structure, which can move freely along the layers.

115. Which one of the following statements is not correct ?

Which one of the following statements is not correct ?

[amp_mcq option1=”Bleaching powder is prepared by the action of Chlorine on dry slaked lime [Ca(OH)2]” option2=”Bleaching powder acts as a reducing agent in many chemical industries” option3=”Bleaching powder is also known as chlorinated lime” option4=”Bleaching powder is used for disinfecting drinking water” correct=”option2″]

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UPSC CAPF – 2016
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Statement B is incorrect. Bleaching powder (Calcium oxychloride, CaOCl₂) is a strong oxidizing agent due to the presence of available chlorine. It acts as an oxidizing agent in bleaching processes and disinfection, not a reducing agent. Reducing agents donate electrons or hydrogen atoms, while oxidizing agents accept electrons or remove hydrogen atoms. Bleaching powder facilitates oxidation reactions.
Understanding the chemical properties of common substances like bleaching powder, specifically its role as an oxidizing agent, is important.
Statement A is correct: Bleaching powder is prepared by passing chlorine gas over dry slaked lime [Ca(OH)₂]. The reaction is Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O.
Statement C is correct: Bleaching powder is also known as chlorinated lime or calcium hypochlorite.
Statement D is correct: Bleaching powder is widely used for disinfecting drinking water, swimming pools, and sanitation purposes because its oxidizing action kills bacteria and other microorganisms.

116. Match List I with List II and select the correct answer using the code

Match List I with List II and select the correct answer using the code given below the Lists :

List I
(Isotope)		List II
(Application)
A. Carbon1. Treatment of goitre
B. Cobalt2. Calculation of age of the earth
C. Iodine3. Treatment of cancer
D. Uranium4. Fuel in nuclear reactors

Code :

[amp_mcq option1=”2 3 1 4″ option2=”2 1 3 4″ option3=”4 1 3 2″ option4=”4 3 1 2″ correct=”option1″]

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The correct answer is A) 2 3 1 4.
– B. Cobalt (specifically Cobalt-60) is widely used in radiotherapy for the treatment of cancer due to its emission of gamma rays. This matches with application 3.
– C. Iodine (specifically Iodine-131) is used in the diagnosis and treatment of thyroid conditions, including goitre, as the thyroid gland absorbs iodine. This matches with application 1.
– D. Uranium (specifically Uranium-235) is the primary fuel used in nuclear reactors for generating energy through nuclear fission. Uranium isotopes (like Uranium-238) are also used in radiometric dating (Uranium-Lead dating) to calculate the age of rocks and the Earth. Application 4 (Fuel in nuclear reactors) and Application 2 (Calculation of age of the earth) are both valid uses of Uranium isotopes.
– A. Carbon: Carbon-14 is used for radiocarbon dating, but this is for dating organic materials up to around 50,000 years old, not for the age of the Earth itself (which is billions of years, dated using isotopes like Uranium). Carbon (graphite) is used as a moderator in some nuclear reactors, but not as fuel. Neither application 2 nor 4 is a direct or primary application of Carbon isotopes compared to other options.
Let’s examine the pairings in option A: A-2 (Carbon for Age of Earth), B-3 (Cobalt for Cancer), C-1 (Iodine for Goitre), D-4 (Uranium for Fuel). B-3, C-1, and D-4 are correct pairings. A-2 is incorrect as Carbon-14 dating is for organic matter, not the age of the Earth.
Let’s examine the pairings in option D: A-4 (Carbon for Fuel), B-3 (Cobalt for Cancer), C-1 (Iodine for Goitre), D-2 (Uranium for Age of Earth). B-3, C-1, and D-2 are correct pairings. A-4 is incorrect as Carbon is a moderator, not fuel, in reactors.
Both option A and D contain correct pairings for B and C. Both contain a correct pairing for D (either 2 or 4, as both are valid uses). Both contain an incorrect pairing for A. Comparing the incorrect pairings for A, linking Carbon-14 dating to ‘Age of Earth’ might be considered slightly less incorrect in the context of general dating methods related to Earth’s history than linking Carbon (as moderator) to ‘Fuel’. Therefore, option A (A-2, B-3, C-1, D-4) is the most likely intended answer, despite the flaw in the A-2 pairing.

117. Which one of the following is not a colloid ?

Which one of the following is not a colloid ?

[amp_mcq option1=”Milk” option2=”Mud” option3=”Butter” option4=”Boric acid” correct=”option4″]

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UPSC CAPF – 2016
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The correct answer is Boric acid.
– Colloids are heterogeneous mixtures where the solute particles are dispersed evenly throughout the solvent as particles that are intermediate in size between those in true solutions and those in suspensions. Colloidal particles typically have a size between 1 nanometer and 1 micrometer.
– True solutions have particle sizes less than 1 nm. Suspensions have particle sizes greater than 1 micrometer, and the particles tend to settle out over time.
– Milk is an emulsion, which is a type of colloid where liquid droplets are dispersed in another liquid.
– Butter is also an emulsion, a type of colloid.
– Mud is primarily a suspension, where solid particles (soil, clay, silt) are dispersed in water. While mud can contain some clay particles of colloidal size, it is generally classified as a suspension because the larger particles settle out.
– Boric acid (H₃BO₃) is a molecular substance that dissolves in water to form a true solution. The particles in a boric acid solution are hydrated boric acid molecules, which are of molecular size, much smaller than colloidal particles.
The Tyndall effect (scattering of light) is a characteristic property of colloids, but not of true solutions. Suspensions may also scatter light, but they are unstable and settle. Boric acid solution will not show the Tyndall effect, unlike milk or muddy water (though settling occurs in mud).

118. A change of state directly from solid to gas without changing into liq

A change of state directly from solid to gas without changing into liquid state is called :

[amp_mcq option1=”Fusion” option2=”Sublimation” option3=”Diffusion” option4=”Emulsion” correct=”option2″]

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UPSC CAPF – 2016
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A change of state directly from solid to gas without changing into liquid state is called sublimation.
The transition of a substance directly from the solid to the gas state, without passing through the liquid state, is known as sublimation. This process occurs when the substance absorbs enough energy to overcome the intermolecular forces holding it in a solid state, but at a pressure and temperature where the liquid phase is unstable or does not exist.
– Fusion (Melting) is the transition from solid to liquid.
– Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration.
– Emulsion is a mixture of two or more liquids that are normally immiscible.
Sublimation is an endothermic process (requires heat). The reverse process, where a gas directly changes to a solid, is called deposition or desublimation. Common examples of substances that readily sublime include dry ice (solid CO2), iodine, and naphthalene.

119. Heavy water of an atomic reactor is :

Heavy water of an atomic reactor is :

[amp_mcq option1=”deionised water” option2=”an oxide of heavier isotope of oxygen” option3=”a mixture of ice and water” option4=”an oxide of heavier isotope of hydrogen” correct=”option4″]

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UPSC CAPF – 2015
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Heavy water is an oxide of a heavier isotope of hydrogen.
Heavy water has the chemical formula D₂O, where D represents Deuterium. Deuterium is an isotope of hydrogen that contains one proton and one neutron in its nucleus (whereas common hydrogen, Protium, has only one proton). Thus, deuterium is a heavier isotope of hydrogen. Heavy water (D₂O) is water composed of two deuterium atoms and one oxygen atom.
Heavy water is used in some types of nuclear reactors (like CANDU reactors) as a neutron moderator and coolant. Its function as a moderator is to slow down neutrons, making them more likely to cause nuclear fission in Uranium fuel. D₂O is more effective as a moderator than ordinary water (H₂O) because deuterium absorbs fewer neutrons than protium. Ordinary water also contains a very small natural abundance of D₂O (about 1 part in 6400). Isotopes of oxygen exist (e.g., ¹⁶O, ¹⁷O, ¹⁸O), and water made with ¹⁸O (H₂¹⁸O) is sometimes called “heavy-oxygen water”, but “heavy water” typically refers to D₂O.

120. The heaviest element known up till January 2015 has the atomic number

The heaviest element known up till January 2015 has the atomic number :

[amp_mcq option1=”117″ option2=”118″ option3=”119″ option4=”120″ correct=”option2″]

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UPSC CAPF – 2015
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As of January 2015, the element with the highest atomic number that had been synthesized and reported was Element 118, Oganesson (Og). While its official naming and addition to the periodic table by IUPAC/IUPAP occurred later, its synthesis was first reported in 2002 and confirmed in 2006 by a Russian-American collaboration. Element 117 (Tennessine, Ts) synthesis was reported in 2010 and confirmed in 2014. Thus, both 117 and 118 were “known” (synthesized) before January 2015, with 118 having the highest atomic number.
The question asks for the element with the highest atomic number *known* up until a certain date, which refers to elements that have been synthesized and their existence tentatively accepted by the scientific community, even if not fully confirmed or officially named.
The heaviest elements are synthetic and highly unstable, existing for only fractions of a second. Elements with atomic numbers 113, 115, 117, and 118 were officially added to the periodic table by IUPAC in December 2015 and named in 2016. Elements 119 and 120 were theoretical or subjects of ongoing synthesis attempts by January 2015.
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