UPSC CAPF Archives

31. 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. Melamine	1. Linear
B. Polyvinyl chloride	2. Condensation
C. Terylene	3. Natural
D. Cellulose	4. Cross-linked

Code :

A-3, B-2, C-1, D-4

A-4, B-1, C-2, D-3

A-3, B-1, C-2, D-4

A-4, B-2, C-1, D-3

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UPSC CAPF – 2018

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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.

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

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

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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.

1 and 2 only

2 and 3 only

1 only

1, 2 and 3

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Answer is Wrong!

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UPSC CAPF – 2018

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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.

33. The term LASER stands for

The term LASER stands for

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Light Amplification by Stimulated Emission of Radiation

Light Amplification by Spontaneous Emission of Radiation

Light Amplification by Stimulated Emission of Rays

Light Amplification by Stimulated Energy of Radiation

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UPSC CAPF – 2018

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The term LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.

LASER is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The full form reflects the fundamental principle behind its operation.

The first working laser was demonstrated in 1960 by Theodore Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow, building on the principles established by Albert Einstein regarding stimulated emission.

34. If the amplitude of oscillation of a simple pendulum is very small, th

If the amplitude of oscillation of a simple pendulum is very small, then its time period of oscillation

1. depends on the length of the pendulum, L
2. depends on the acceleration due to gravity, g
3. depends upon the mass of the bob of the pendulum, m
4. does not depend upon the amplitude of the pendulum, A

Select the correct answer using the code given below.

1, 2 and 3

1, 2 and 4

2, 3 and 4

1 and 4 only

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Answer is Wrong!

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UPSC CAPF – 2018

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The time period of oscillation of a simple pendulum, when the amplitude is very small, depends on the length of the pendulum and the acceleration due to gravity, but not on the mass of the bob or the amplitude.

For small oscillations (amplitude A is very small), the formula for the time period (T) of a simple pendulum is given by T = 2π√(L/g), where L is the length of the pendulum and g is the acceleration due to gravity. This formula explicitly shows that the time period depends on L and g, but it does not contain the mass (m) of the bob or the amplitude (A). The condition of small amplitude is crucial for this simplified formula to hold, implying independence from amplitude in this specific case.

For larger amplitudes, the time period of a simple pendulum is slightly longer and does depend on the amplitude. However, the question specifically states “amplitude… is very small”, which validates the use of the small-angle approximation formula.

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35. Which one of the following statements about transport mechanism in pla

Which one of the following statements about transport mechanism in plants is correct?

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Diffusion of ions and small molecules across cell membrane requires energy.

Active transport of ions and small molecules across cell membrane against concentration gradient requires energy.

Cells conserve energy and no energy is required for transport of ions and small molecules against concentration gradient.

Cells do not transport ions across their membrane as these are charged molecules.

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Answer is Wrong!

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UPSC CAPF – 2018

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The correct answer is B) Active transport of ions and small molecules across cell membrane against concentration gradient requires energy.

Statement A is incorrect: Diffusion (simple or facilitated) is a passive process driven by the concentration gradient; it does not require metabolic energy (ATP).
Statement B is correct: Active transport involves moving substances across a cell membrane against their concentration gradient (from a region of lower concentration to a region of higher concentration). This process requires the cell to expend metabolic energy, usually in the form of ATP, to power transport proteins (pumps).
Statement C is incorrect: Moving substances against a concentration gradient requires energy input. Cells use active transport precisely for this purpose, even though it consumes energy.
Statement D is incorrect: Cells regularly transport ions across their membranes using both passive mechanisms (ion channels) and active mechanisms (ion pumps) to maintain electrochemical gradients, osmotic balance, and for signalling. Ions are charged molecules, but their transport is essential for cell function.

Transport across cell membranes can be broadly classified into passive transport (diffusion, facilitated diffusion) and active transport. Passive transport does not require energy input and follows concentration gradients. Active transport requires energy and can move substances against gradients. Plants, like other organisms, use both types of transport for uptake of nutrients from the soil and for movement of substances within the plant.

36. Which one of the following statements about proteins in mammalian cell

Which one of the following statements about proteins in mammalian cells is correct?

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Proteins in mammalian cells are synthesized in cell membrane.

Proteins in mammalian cells are not synthesized in cell membrane but directly absorbed from food.

Proteins in mammalian cells are synthesized in rough endoplasmic reticulum.

Proteins in mammalian cells are synthesized in Golgi apparatus.

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Answer is Wrong!

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UPSC CAPF – 2018

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The correct answer is C) Proteins in mammalian cells are synthesized in rough endoplasmic reticulum.

Protein synthesis, or translation, occurs on ribosomes. Ribosomes can be found freely in the cytoplasm or attached to the surface of the endoplasmic reticulum, forming the rough endoplasmic reticulum (RER). Proteins destined for secretion out of the cell, insertion into cell membranes (including the plasma membrane and membranes of organelles like RER, Golgi, lysosomes), or delivery to organelles within the secretory pathway (like lysosomes) are synthesized on ribosomes attached to the RER. Proteins destined for the cytoplasm, nucleus, mitochondria, or peroxisomes are typically synthesized on free ribosomes in the cytoplasm. Therefore, the rough endoplasmic reticulum is a major site of protein synthesis in mammalian cells, particularly for proteins entering the secretory pathway.

Statement A is incorrect; the cell membrane is where some proteins reside, but not where they are synthesized. Statement B is incorrect; cells synthesize their own proteins from amino acids. Statement D is incorrect; the Golgi apparatus modifies, sorts, and packages proteins synthesized elsewhere, but does not synthesize them.

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

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

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2 and 1

1 and 2

3 and 1

4 and 0

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UPSC CAPF – 2018

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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*.

38. Lowering the atmospheric pressure on a liquid

Lowering the atmospheric pressure on a liquid

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increases the boiling point of the liquid

lowers the boiling point of the liquid

does not affect the boiling point of the liquid

increases the time required for it to boil

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Answer is Wrong!

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UPSC CAPF – 2018

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The correct answer is B) lowers the boiling point of the liquid.

Boiling point is defined as the temperature at which the vapor pressure of a liquid equals the surrounding atmospheric pressure. When the atmospheric pressure is lowered, the liquid needs to reach a lower vapor pressure to start boiling. Since vapor pressure increases with temperature, a lower required vapor pressure is achieved at a lower temperature. Therefore, lowering the atmospheric pressure on a liquid lowers its boiling point.

This principle is why water boils at a lower temperature at high altitudes (where atmospheric pressure is lower) than at sea level. For example, water boils at 100°C at standard atmospheric pressure (1 atm), but at approximately 93°C in Denver, Colorado (altitude ~1600m), and even lower on top of Mount Everest. Conversely, increasing the pressure (e.g., in a pressure cooker) increases the boiling point of water, allowing food to cook faster.

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

Which one of the following gemstones contains beryllium metal?

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Topaz

Emerald

Ruby

Blue sapphire

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UPSC CAPF – 2018

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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.

40. Which of the following statements about optical microscope is/are corr

Which of the following statements about optical microscope is/are correct?

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1. Both the eyepiece and objective of a microscope are convex lenses.
2. The magnification of a microscope increases with increase in focal length of the objective.
3. The magnification of a microscope depends upon the length of the microscope tube.
4. The eyepiece of a microscope is a concave lens.

Select the correct answer using the code given below.

1 and 3

3 only

3 and 4

1, 2 and 4

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Answer is Wrong!

This question was previously asked in

UPSC CAPF – 2018

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The correct answer is A) 1 and 3.

Statement 1 is correct: In a standard compound optical microscope, both the objective lens (or lens system) and the eyepiece lens (or lens system) act as convex lenses to produce magnification. The objective creates a magnified real intermediate image, and the eyepiece magnifies this intermediate image to form a virtual final image.
Statement 2 is incorrect: The magnification of the objective lens is inversely proportional to its focal length. A shorter focal length objective provides higher magnification (and typically lower depth of field and working distance).
Statement 3 is correct: The overall magnification of a compound microscope is approximately the product of the magnification of the objective and the magnification of the eyepiece. The magnification provided by the objective is related to the distance between the objective and the intermediate image (which is determined by the microscope’s tube length) and the focal length of the objective. Thus, the length of the microscope tube affects the magnification.
Statement 4 is incorrect: As mentioned in statement 1, the eyepiece acts as a magnifying glass, which is achieved using a convex lens or a combination of lenses that function as a convex lens.

The total magnification of a compound microscope is typically calculated as M_total = M_objective × M_eyepiece. The objective magnification is often given by M_objective ≈ L / f_objective, where L is the mechanical tube length and f_objective is the focal length of the objective. This confirms that tube length (L) affects the magnification.