UPSC NDA-2

41. Which of the following anions has a valency of –3 ?

Which of the following anions has a valency of –3 ?

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Nitride
Nitrate
Sulphide
Sulphate
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The correct answer is A) Nitride.
Valency, in the context of ions, refers to the magnitude of the charge on the ion. An anion is a negatively charged ion.
– Nitride is the anion formed from a nitrogen atom gaining electrons to achieve a stable electron configuration. Nitrogen is in Group 15 and typically gains 3 electrons to form N³⁻. Thus, the valency of the nitride ion is -3.
– Nitrate is the polyatomic anion NO₃⁻, with an overall charge of -1.
– Sulphide is the anion formed from a sulphur atom gaining electrons. Sulphur is in Group 16 and typically gains 2 electrons to form S²⁻. The valency of the sulphide ion is -2.
– Sulphate is the polyatomic anion SO₄²⁻, with an overall charge of -2.
The charge on the ion directly corresponds to its valency (with the sign indicating whether it’s a cation or anion). Therefore, the anion with a valency of -3 is Nitride (N³⁻).

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42. Which one among the following elements is polyatomic ?

Which one among the following elements is polyatomic ?

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Phosphorus
Sulphur
Chlorine
Aluminium
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The correct answer is B) Sulphur.
An element is considered polyatomic if its stable molecular form consists of more than two atoms of that element bonded together. Sulphur exists in various allotropes, the most common and stable form being the S₈ molecule, which has a ring structure containing eight sulphur atoms. This makes sulphur a polyatomic element.
Chlorine exists as diatomic molecules (Cl₂). Aluminium is a metal and exists as individual atoms in its elemental state (monatomic in solid form). Phosphorus exists in various allotropes, such as white phosphorus (P₄, tetratomic) and red phosphorus (polymeric). While Phosphorus (P₄) is also polyatomic, Sulphur (S₈) is a common example used to illustrate polyatomic elements in chemistry, and it is explicitly polyatomic in its stable form. Given the options and the need for a single correct answer, S₈ is a clear example of a polyatomic molecule.

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43. Which one among the following separation techniques is used for blood

Which one among the following separation techniques is used for blood tests in diagnostic laboratories ?

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Filtration
Chromatography
Centrifugation
Crystallization
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The correct answer is C) Centrifugation.
Centrifugation is a separation technique used to separate particles from a liquid solution by spinning the solution at high speed in a centrifuge. Denser components move away from the axis of rotation, while lighter components move towards the axis. In diagnostic laboratories, centrifugation is routinely used for blood tests to separate blood components like plasma, red blood cells, white blood cells, and platelets, enabling various analyses on these different fractions.
Filtration is used to separate insoluble solids from a liquid using a filter medium. Chromatography is used to separate mixtures based on differences in partitioning between a stationary phase and a mobile phase. Crystallization is a technique used to separate a solid substance from a liquid solution by forming crystals. None of these are the primary method for separating blood components in a standard blood test.

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44. The intermixing of particles of two different types of matter on their

The intermixing of particles of two different types of matter on their own is called

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Osmosis
Brownian motion
Diffusion
Conductance
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The correct answer is C) Diffusion.
Diffusion is the net movement of anything generally from a region of higher concentration to a region of lower concentration. This movement is driven by the random motion of particles (molecules or atoms) leading to their spontaneous intermixing until the concentration is uniform throughout. The intermixing of particles of two different types of matter on their own is the definition of diffusion.
Osmosis is a specific type of diffusion involving the movement of solvent molecules (usually water) across a semipermeable membrane from a region of high solvent concentration to a region of low solvent concentration. Brownian motion is the random movement of microscopic particles suspended in a liquid or gas, caused by collisions with the molecules of the surrounding medium; it is the underlying cause of diffusion but not the intermixing process itself. Conductance refers to the ability of a material to conduct electricity.

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45. In which one among the following the vegetative propagation takes plac

In which one among the following the vegetative propagation takes place through Eye Buds ?

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Potato
Ginger
Onion
Sugarcane
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The correct answer is A) Potato.
Vegetative propagation is a form of asexual reproduction in plants where new individuals are produced from vegetative parts like roots, stems, leaves, and buds. In potatoes, the underground stem (tuber) has structures called ‘eyes’, which are actually dormant buds. Each eye can grow into a new potato plant under favourable conditions.
Other plants also exhibit vegetative propagation through different structures: Ginger propagates through rhizomes (underground stems) which have nodes and buds. Onion propagates through bulbs, which are modified stems with fleshy leaves containing buds. Sugarcane propagates through stem cuttings which have nodes and buds. While all these involve buds, the term ‘eye buds’ is specifically associated with the potato tuber.

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46. Which one among the following is the source of energy in cells ?

Which one among the following is the source of energy in cells ?

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ADP
ATP
AMP
NAD
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Adenosine Triphosphate (ATP) is the primary source of energy in cells.
ATP is often referred to as the energy currency of the cell because it stores and transfers energy released from metabolic reactions to power cellular activities.
Energy is released when ATP is hydrolyzed to ADP (Adenosine Diphosphate) and inorganic phosphate. ADP can be re-phosphorylated to ATP using energy from catabolic processes like cellular respiration. AMP (Adenosine Monophosphate) and NAD (Nicotinamide adenine dinucleotide) are also important molecules in metabolism but ATP is the direct energy source for most cellular work.

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47. Which one among the following tissues help to connect two bones ?

Which one among the following tissues help to connect two bones ?

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Tendons
Ligaments
Areolar tissue
Cartilage
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Ligaments are the type of connective tissue that helps to connect two bones together.
Ligaments are strong, fibrous bands that stabilize joints by holding bones in place.
Tendons connect muscles to bones. Areolar tissue is a loose connective tissue that fills spaces and supports organs. Cartilage is a specialized connective tissue providing cushioning and support, found in joints but not primarily connecting bones to each other across a joint; that’s the role of ligaments.

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48. Which of the following two cell organelles have their own genetic mate

Which of the following two cell organelles have their own genetic material ?

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Endoplasmic reticulum and plastids
Endoplasmic reticulum and mitochondria
Mitochondria and plastids
Lysosomes and Golgi apparatus
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Mitochondria and plastids are the two cell organelles in eukaryotic cells that possess their own genetic material (DNA).
This characteristic supports the endosymbiotic theory, which suggests that these organelles originated from prokaryotic organisms engulfed by primitive eukaryotic cells.
The DNA in mitochondria and plastids is typically circular, similar to bacterial DNA, and they also have their own ribosomes and protein synthesis machinery. Endoplasmic reticulum, lysosomes, and Golgi apparatus are part of the endomembrane system and do not have their own DNA.

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49. Which one of the following statements about lysosomes is NOT correct ?

Which one of the following statements about lysosomes is NOT correct ?

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They are waste disposal system of the cell
They breakdown all inorganic materials
These are also referred to as "suicidal bags"
Lysosomes stop entry of foreign materials
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The statement “They breakdown all inorganic materials” is NOT correct about lysosomes.
Lysosomes contain hydrolytic enzymes (like proteases, lipases, carbohydrases, nucleases) that break down organic macromolecules (proteins, lipids, carbohydrates, nucleic acids), waste materials, and cellular debris. They are not equipped to break down inorganic substances.
Statement A is correct as they function in waste disposal. Statement C is correct as they are often called “suicidal bags” because their rupture can lead to the digestion of the cell itself. Statement D is also technically incorrect as lysosomes digest foreign material *after* it has entered the cell (e.g., through phagocytosis), rather than stopping its entry. However, option B is fundamentally wrong about the nature of the substances they break down.

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50. ‘Sengol’, installed in the new Parliament building of India, was seen

‘Sengol’, installed in the new Parliament building of India, was seen as a symbol of the path of service, duty and nation in which Empire of the past?

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Gupta Empire
Shunga Empire
Pandyan Empire
Chola Empire
This question was previously asked in
UPSC NDA-2 – 2023
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The ‘Sengol’, installed in the new Parliament building, is historically associated with the transfer of power in the Chola Empire.
In the Chola tradition, the handing over of the Sengol symbolized the transfer of power from one king to another, representing justice and righteous governance.
A Sengol was presented to Pandit Jawaharlal Nehru on the eve of India’s independence in 1947 by representatives from Tamil Nadu, signifying the transfer of power from the British to India.

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