Chemistry

101. Aluminium, Iron, Copper and Zinc are extracted from

Aluminium, Iron, Copper and Zinc are extracted from

[amp_mcq option1=”Bauxite, Magnetite, Malachite and Calamine respectively” option2=”Magnetite, Bauxite, Malachite and Calamine respectively” option3=”Calamine, Malachite, Magnetite and Bauxite respectively” option4=”Malachite, Magnetite, Bauxite and Calamine respectively” correct=”option1″]

This question was previously asked in
UPSC CAPF – 2019
Download PDFAttempt Online
The correct option is A.
Aluminium is primarily extracted from Bauxite ore (hydrated aluminium oxide, Al₂O₃·nH₂O). Iron is commonly extracted from Magnetite (Fe₃O₄) or Hematite (Fe₂O₃). Copper is extracted from various ores, including Malachite (copper carbonate hydroxide, Cu₂(CO₃)(OH)₂) and Chalcopyrite (CuFeS₂). Zinc is extracted from ores like Calamine (Zinc Carbonate, ZnCO₃) or Sphalerite (Zinc Sulphide, ZnS). Option A correctly matches each metal with one of its principal ores in the specified order: Aluminium (Bauxite), Iron (Magnetite), Copper (Malachite), and Zinc (Calamine).
Other important ores for Iron include Hematite, Limonite, and Siderite. Besides Malachite, Cuprite and Azurite are also important copper ores. Sphalerite is another major zinc ore. The extraction processes for these metals involve various stages like mining, concentration, roasting, smelting, and refining.

102. Which one of the following will NOT show Tyndall effect ?

Which one of the following will NOT show Tyndall effect ?

[amp_mcq option1=”Chalk powder freshly mixed with water” option2=”Lime juice” option3=”Few drops of milk mixed with water” option4=”Starch solution” correct=”option2″]

This question was previously asked in
UPSC CAPF – 2019
Download PDFAttempt Online
The Tyndall effect is the scattering of light by colloidal particles in a colloid or a suspension. True solutions, where the solute particles are too small (individual ions or molecules) to scatter light significantly, do not exhibit the Tyndall effect. Among the given options, lime juice is primarily a true solution (containing dissolved sugars, citric acid, etc.), while chalk powder in water (suspension), milk in water (emulsion/colloid), and starch solution (colloid) contain particles large enough to scatter light.
– Tyndall effect is a phenomenon where light is scattered as it passes through a colloid or suspension.
– This scattering makes the path of the light beam visible.
– True solutions do not show the Tyndall effect because the dissolved particles are too small.
The Tyndall effect is a useful way to distinguish between a true solution and a colloid. If a beam of light passed through the mixture is visible, it is likely a colloid or suspension. If the beam is not visible, it is likely a true solution.

103. Which one of the following is known as Wood Spirit ?

Which one of the following is known as Wood Spirit ?

[amp_mcq option1=”Methanol” option2=”Ethanol” option3=”Formaldehyde” option4=”Acetaldehyde” correct=”option1″]

This question was previously asked in
UPSC CAPF – 2019
Download PDFAttempt Online
Methanol (CH3OH) is historically known as wood alcohol or wood spirit because it was traditionally produced by the destructive distillation of wood.
– Methanol is the simplest alcohol.
– It is a volatile, flammable, poisonous liquid.
– Its historical source gave it the common name “wood spirit”.
Ethanol (C2H5OH) is grain alcohol, commonly found in alcoholic beverages. Formaldehyde (HCHO) is an aldehyde used as a preservative and disinfectant. Acetaldehyde (CH3CHO) is another aldehyde, toxic and a metabolic product of ethanol breakdown.

104. Which one of the following is not a condensation polymer?

Which one of the following is not a condensation polymer?

[amp_mcq option1=”Nylon” option2=”DNA” option3=”Polythene” option4=”Bakelite” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2018
Download PDFAttempt Online
Polythene (polyethylene) is formed by the addition polymerization of ethylene monomers (CH2=CH2). In addition polymerization, monomers add to one another without the elimination of any small molecules. Condensation polymerization, on the other hand, involves the reaction between monomers with the elimination of a small molecule such as water (H2O), alcohol, or ammonia.
Condensation polymers are formed with the elimination of a small molecule during polymerization. Addition polymers are formed by the simple addition of monomers without any elimination.
Nylon is a polyamide formed by the condensation reaction between a diamine and a dicarboxylic acid (or between amino acids). Bakelite is a phenol-formaldehyde resin formed by condensation. DNA is a biopolymer where nucleotides are linked by phosphodiester bonds, the formation of which involves the elimination of water (a condensation-like process), but in the context of synthetic polymers, Polythene is the clear example of an addition polymer among the options, making it the one that is *not* a condensation polymer.

105. 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
(Compound)		List-II
(Type of polymer)
A. Melamine1. Linear
B. Polyvinyl chloride2. Condensation
C. Terylene3. Natural
D. Cellulose4. Cross-linked

Code :

[amp_mcq option1=”A-3, B-2, C-1, D-4″ option2=”A-4, B-1, C-2, D-3″ option3=”A-3, B-1, C-2, D-4″ option4=”A-4, B-2, C-1, D-3″ correct=”option2″]

This question was previously asked in
UPSC CAPF – 2018
Download PDFAttempt Online
The correct matching is A-4, B-1, C-2, D-3.
– **Melamine:** Melamine-formaldehyde resin is a thermosetting polymer formed by condensation polymerization, resulting in a rigid, **cross-linked** structure.
– **Polyvinyl chloride (PVC):** Formed from vinyl chloride monomers (CH2=CHCl) via addition polymerization. PVC chains are essentially **linear**.
– **Terylene (PET):** Polyethylene terephthalate is a polyester formed by **condensation** polymerization of ethylene glycol and terephthalic acid.
– **Cellulose:** A naturally occurring polysaccharide found in plant cell walls. It is a **natural** polymer.
Polymers can be classified based on their structure (linear, branched, cross-linked), origin (natural, synthetic), and synthesis method (addition, condensation). Melamine is known for its use in laminates and molded plastics due to its cross-linked structure. PVC is a common thermoplastic used in pipes, cables, etc. Terylene is widely used as a fiber (polyester fabrics) and in bottles. Cellulose is the main component of wood and cotton.

106. Which of the following statements about carboxylic acids is/are correc

Which of the following statements about carboxylic acids is/are correct?

  • 1. Simple aliphatic carboxylic acids are soluble in water.
  • 2. Higher carboxylic acids are practically insoluble in water.
  • 3. The acidity of a carboxylic acid depends on the number of carbon atoms present in the hydrocarbon chain.

Select the correct answer using the code given below.

[amp_mcq option1=”1 and 2 only” option2=”2 and 3 only” option3=”1 only” option4=”1, 2 and 3″ correct=”option4″]

This question was previously asked in
UPSC CAPF – 2018
Download PDFAttempt Online
All three statements about carboxylic acids are correct.
1. Simple aliphatic carboxylic acids (e.g., formic acid, acetic acid) are soluble in water because the polar carboxyl group (-COOH) can form hydrogen bonds with water molecules.
2. As the hydrocarbon chain length increases in higher carboxylic acids, the nonpolar hydrophobic part dominates, making them practically insoluble in water.
3. The acidity of a carboxylic acid is related to the stability of its conjugate base (carboxylate ion). Alkyl groups are electron-donating, which destabilizes the negative charge on the carboxylate ion. Therefore, increasing the number of carbon atoms (length of the alkyl chain) generally decreases the acidity of aliphatic carboxylic acids. The hydrocarbon chain’s size *does* influence acidity.
Conversely, electron-withdrawing groups (like halogens, nitro groups) attached to the hydrocarbon chain increase the acidity by stabilizing the conjugate base through inductive effects or resonance. For aromatic carboxylic acids (like benzoic acid), substituents on the ring also affect acidity.

107. The number of angular and radial nodes for 4d orbital is respectively

The number of angular and radial nodes for 4d orbital is respectively

[amp_mcq option1=”2 and 1″ option2=”1 and 2″ option3=”3 and 1″ option4=”4 and 0″ correct=”option1″]

This question was previously asked in
UPSC CAPF – 2018
Download PDFAttempt Online
The correct answer is A) 2 and 1.
For an atomic orbital described by the principal quantum number *n* and azimuthal (angular momentum) quantum number *l*:
– The number of angular nodes is equal to *l*.
– The total number of nodes is equal to *n* – 1.
– The number of radial nodes is the total number of nodes minus the number of angular nodes, i.e., (*n* – 1) – *l*.
For a 4d orbital:
– Principal quantum number *n* = 4.
– For a d orbital, the azimuthal quantum number *l* = 2 (s=0, p=1, d=2, f=3).
– Number of angular nodes = *l* = 2.
– Number of radial nodes = (*n* – 1) – *l* = (4 – 1) – 2 = 3 – 2 = 1.
The question asks for the number of angular and radial nodes *respectively*.
Angular nodes are surfaces where the probability of finding the electron is zero, and their shape depends on the value of *l* (e.g., for p orbitals, the angular node is a plane; for d orbitals, there are two angular nodes, often planes or conical surfaces). Radial nodes are spherical surfaces where the radial probability density (probability per unit volume) is zero. The number of radial nodes depends on both *n* and *l*.

108. Which one of the following gemstones contains beryllium metal?

Which one of the following gemstones contains beryllium metal?

[amp_mcq option1=”Topaz” option2=”Emerald” option3=”Ruby” option4=”Blue sapphire” correct=”option2″]

This question was previously asked in
UPSC CAPF – 2018
Download PDFAttempt Online
The correct answer is B) Emerald.
Emerald is a variety of the mineral beryl, with the chemical formula Be₃Al₂(SiO₃)₆. The chemical composition clearly shows the presence of Beryllium (Be) metal. The green color of emerald comes from trace amounts of chromium or vanadium within the crystal lattice.
Let’s look at the composition of the other gemstones:
– Topaz: Aluminium and fluorine silicate (Al₂SiO₄(F,OH)₂). Contains Aluminium, Silicon, Oxygen, Fluorine, Hydrogen.
– Ruby and Blue Sapphire: Both are varieties of the mineral corundum, which is aluminium oxide (Al₂O₃). Ruby is colored by chromium, and sapphire by iron and titanium.
Thus, out of the given options, only Emerald contains beryllium.

109. Carborundum is used as an abrasive, because it

Carborundum is used as an abrasive, because it

[amp_mcq option1=”has high thermal conductivity” option2=”has low coefficient of expansion” option3=”has high chemical stability” option4=”is extremely hard” correct=”option4″]

This question was previously asked in
UPSC CAPF – 2017
Download PDFAttempt Online
The correct option is D.
Carborundum, also known as Silicon Carbide (SiC), is widely used as an abrasive primarily because it is extremely hard. Abrasive materials work by scratching or grinding away the surface of other materials, a process that requires the abrasive to be harder than the material being abraded. Carborundum is one of the hardest known materials, ranking high on the Mohs scale of hardness (around 9-9.5), making it effective for grinding and cutting hard substances.
While carborundum possesses other properties listed, such as high thermal conductivity (A) and high chemical stability (C), these properties are not the primary reason for its use as an abrasive. Low coefficient of expansion (B) contributes to its thermal shock resistance, useful in high-temperature applications, but is not the fundamental reason for its abrasiveness.

110. Which one of the following is the chemical name of heavy water ?

Which one of the following is the chemical name of heavy water ?

[amp_mcq option1=”Hydrogen oxide” option2=”Deuterium dioxide” option3=”Deuterium oxide” option4=”Heavy hydrogen oxide” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2017
Download PDFAttempt Online
Heavy water is a form of water in which the hydrogen atoms are replaced by deuterium, an isotope of hydrogen with one proton and one neutron (compared to normal hydrogen, protium, which has one proton and no neutrons). The chemical formula for heavy water is D₂O or ²H₂O. The standard chemical name for D₂O is Deuterium oxide.
Heavy water is water composed of deuterium and oxygen. Deuterium is an isotope of hydrogen.
Heavy water is used primarily as a moderator and coolant in certain types of nuclear reactors (specifically, Pressurized Heavy-Water Reactors like the CANDU reactor) because deuterium absorbs fewer neutrons than normal hydrogen.
Page 1Page 2Page 3Page 4Page 5