UPSC NDA-1

31. ‘Campos’ and ‘Llanos’, Tropical Savanna grasslands are generally found

‘Campos’ and ‘Llanos’, Tropical Savanna grasslands are generally found in

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Australia
Central Africa
South America
East Asia
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‘Campos’ and ‘Llanos’, Tropical Savanna grasslands are generally found in South America.
‘Campos’ refers to the tropical savanna grasslands primarily found in Brazil, particularly the Cerrado region. ‘Llanos’ refers to the vast tropical grassland plain stretching across parts of Venezuela and Colombia. Both are prominent savanna ecosystems located in South America. While tropical savannas exist in other continents like Africa and Australia, the terms ‘Campos’ and ‘Llanos’ are specific to South America.
Tropical savannas are grasslands with scattered trees, found in regions with distinct wet and dry seasons. Other famous tropical savanna regions include the Serengeti in East Africa and the Australian savanna. Different regions use different local names for these ecosystems. For example, in Africa, they are often just called ‘savanna’ or specific regional names, and in Australia, they are also referred to as ‘savanna’ or ‘tropical grasslands’.

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32. National Water Academy, a centre of excellence in training and capacit

National Water Academy, a centre of excellence in training and capacity building in water resource, is located at

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New Delhi
Kolkata
Pune
Chennai
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The National Water Academy is located at Pune.
The National Water Academy (NWA) is a premier institution for training and capacity building in the field of water resources development and management in India. It is under the Central Water Commission (CWC), Ministry of Jal Shakti, Department of Water Resources, River Development and Ganga Rejuvenation, Government of India. The academy is situated in Pune, Maharashtra.
The NWA organises training programs, workshops, and seminars for engineers and professionals involved in water resources development and management from Central and State government departments, Public Sector Undertakings, and other organisations. It aims to impart knowledge and skills in various aspects of water resources engineering, planning, and management.

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33. Which one of the following is NOT true in reference to Air mass ?

Which one of the following is NOT true in reference to Air mass ?

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Air mass forms either in tropical or in polar region
Air mass develops on continents as well as over ocean
Air mass develops in a cyclonic condition
Air mass changes the weather conditions
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It is NOT true that Air mass develops in a cyclonic condition.
An air mass is a large volume of air that has relatively uniform temperature and moisture characteristics throughout, acquired from its source region.
A) Air mass forms either in tropical or in polar region: True. Source regions are typically large, homogeneous areas like tropical oceans, polar continents, etc.
B) Air mass develops on continents as well as over ocean: True. Source regions can be continental (cA, cT) or maritime (mA, mT).
C) Air mass develops in a cyclonic condition: False. Cyclonic conditions involve convergence and uplift, leading to mixing and non-uniformity. Air masses form in areas of stable, stagnant, or slow-moving air, usually under high pressure (anticyclonic) conditions where the air resides long enough to take on the characteristics of the underlying surface.
D) Air mass changes the weather conditions: True. When an air mass moves from its source region to another area, it brings its characteristic temperature and moisture properties, influencing the weather of the new region.
Source regions for air masses are typically high-pressure areas because the air in such systems is stable and subsides, allowing it to remain over a region for sufficient time to acquire uniform properties. Low-pressure systems (cyclones) are dynamic zones of converging and lifting air, which are not conducive to the formation of homogeneous air masses. Instead, cyclones often form along the boundaries (fronts) between different air masses.

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34. Which one of the following is used as a binder in paints ?

Which one of the following is used as a binder in paints ?

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Titanium dioxide
Novolac
Phthalocyanine
Silicones
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Novolac is used as a binder in paints.
In paint formulation, a binder (also known as the vehicle) is the component that forms a film to hold the pigment particles together and adhere them to the surface being painted. Titanium dioxide and Phthalocyanine are examples of pigments, which provide color and opacity. Silicones are polymers that can be used in paints, often as additives for properties like water repellency or flexibility, or as binders in specialized coatings, but Novolac (a type of phenolic resin) is a well-established binder, particularly used in durable coatings like primers, can coatings, and industrial finishes due to its excellent chemical resistance and hardness.
Common binders in paints include acrylics, alkyds, epoxies, polyurethanes, and phenolic resins like Novolac. The choice of binder significantly impacts the paint’s properties, such as durability, adhesion, gloss, drying time, and resistance to chemicals and weather. Pigments like titanium dioxide (white) and phthalocyanines (blue/green) provide color and opacity but do not bind the paint components together.

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35. In which of the following pairs are the ions isoelectronic ?

In which of the following pairs are the ions isoelectronic ?

Mg$^{2+}$, Ar
Na$^{+}$, O$^{2-}$
Al$^{3+}$, Cl$^{-}$
K$^{+}$, Ne
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The pair Na⁺ and O²⁻ are isoelectronic.
Isoelectronic species are atoms or ions that have the same number of electrons. Let’s check the electron count for each species:
– Mg²⁺: Magnesium (Mg) has atomic number 12, so it has 12 electrons. Mg²⁺ has lost 2 electrons, so it has 10 electrons.
– Ar: Argon (Ar) has atomic number 18, so it has 18 electrons.
– Na⁺: Sodium (Na) has atomic number 11, so it has 11 electrons. Na⁺ has lost 1 electron, so it has 10 electrons.
– O²⁻: Oxygen (O) has atomic number 8, so it has 8 electrons. O²⁻ has gained 2 electrons, so it has 10 electrons.
– Al³⁺: Aluminum (Al) has atomic number 13, so it has 13 electrons. Al³⁺ has lost 3 electrons, so it has 10 electrons.
– Cl⁻: Chlorine (Cl) has atomic number 17, so it has 17 electrons. Cl⁻ has gained 1 electron, so it has 18 electrons.
– K⁺: Potassium (K) has atomic number 19, so it has 19 electrons. K⁺ has lost 1 electron, so it has 18 electrons.
– Ne: Neon (Ne) has atomic number 10, so it has 10 electrons.

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Comparing the pairs:
A) Mg²⁺ (10e⁻), Ar (18e⁻) – Not isoelectronic.
B) Na⁺ (10e⁻), O²⁻ (10e⁻) – Isoelectronic.
C) Al³⁺ (10e⁻), Cl⁻ (18e⁻) – Not isoelectronic.
D) K⁺ (18e⁻), Ne (10e⁻) – Not isoelectronic.

Many ions of elements close to noble gases are isoelectronic with the nearest noble gas. For example, Na⁺, Mg²⁺, Al³⁺, O²⁻, F⁻ are all isoelectronic with Neon (10 electrons). K⁺, Ca²⁺, S²⁻, Cl⁻ are all isoelectronic with Argon (18 electrons). Isoelectronic species often have similar chemical properties related to their electron configuration.

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36. Which one of the following metals does NOT react with cold water ?

Which one of the following metals does NOT react with cold water ?

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Calcium (Ca)
Potassium (K)
Magnesium (Mg)
Sodium (Na)
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Magnesium (Mg) does NOT react with cold water.
Alkali metals (like Potassium and Sodium) react vigorously or even explosively with cold water, producing hydrogen gas and their hydroxides. Calcium, an alkaline earth metal, also reacts with cold water, albeit less vigorously than sodium or potassium, forming calcium hydroxide and hydrogen gas. Magnesium, another alkaline earth metal, reacts very slowly with boiling water and reacts readily with steam to form magnesium oxide and hydrogen, but it does not react with cold water.
The reactivity of these metals with water increases down the group for alkali metals (Li < Na < K < Rb < Cs) and generally for alkaline earth metals (Be < Mg < Ca < Sr < Ba), although the trend for alkaline earth metals reacting with cold water starts effectively at Calcium. Beryllium does not react with water or steam.

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37. Which one of the following is an example of a clean fuel ?

Which one of the following is an example of a clean fuel ?

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Coke
Propane
Petrol
Wax
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Propane is an example of a clean fuel among the given options.
Clean fuels produce less pollution when burned compared to conventional fuels. Propane, being a gaseous fuel (part of LPG – Liquefied Petroleum Gas), generally burns more cleanly than solid fuels like coke or liquid fuels like petrol and wax, which produce significant amounts of smoke, particulate matter, and other pollutants like sulfur oxides and nitrogen oxides. While no fuel is perfectly “clean,” propane is significantly cleaner than the other options listed in terms of common air pollutants.
Common examples of cleaner fuels include natural gas (methane), LPG (propane and butane), hydrogen, and biofuels like ethanol and biodiesel (though the ‘cleanliness’ of biofuels is debated depending on production). Coke is a solid fuel derived from coal, primarily carbon, and its combustion produces significant air pollution. Petrol (gasoline) is a complex mix of hydrocarbons used in internal combustion engines and is a major source of air pollution. Wax is a solid hydrocarbon often used in candles or as fuel, producing smoke and particulates when burned.

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38. Which one of the following is NOT a synthetic detergent ?

Which one of the following is NOT a synthetic detergent ?

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”CH$_3$(CH$_2$)$_{10}$CH$_2$O
”[CH$_3$(CH$_2$)$_{15}$–N–(CH$_3$)$_3$
$^{+}$ Br$^{-}$” option3=”CH$_3$(CH$_2$)$_{16}$COO$^{-}$ Na$^{+}$” option4=”CH$_3$(CH$_2$)$_{16}$COO(CH$_2$CH$_2$O)$_n$ CH$_2$CH$_2$OH” correct=”option3″]

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The correct answer is C) CH$_3$(CH$_2$)$_{16}$COO$^{-}$ Na$^{+}$.
Synthetic detergents are cleaning agents that are synthesized and have chemical structures different from traditional soaps. Traditional soaps are salts of fatty acids, typically with a carboxylate head group (-COO-). Option C, CH$_3$(CH$_2$)$_{16}$COO$^{-}$ Na$^{+}$, is sodium stearate, which is a common example of a soap. Options A, B, and D represent synthetic detergents with different types of polar head groups: A is an anionic sulfate-based detergent, B is a cationic quaternary ammonium-based detergent, and D is a non-ionic polyoxyethylene-based detergent.
Soaps are derived from the saponification of fats and oils (esters of fatty acids). Synthetic detergents were developed to overcome some limitations of soaps, such as their tendency to form scum with hard water ions. The term “synthetic detergent” typically refers to surfactants other than soaps.

39. Which one of the following minerals is used as a fuel in nuclear power

Which one of the following minerals is used as a fuel in nuclear power stations ?

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Bauxite
Quartz
Feldspar
Pitchblende
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The correct answer is D) Pitchblende.
Nuclear power stations use fissile materials, primarily uranium, as fuel for nuclear fission. Pitchblende is a mineral that is a major ore of uranium. Bauxite is the main ore of aluminium. Quartz is a common mineral made of silicon dioxide. Feldspar is a group of rock-forming silicate minerals. Therefore, Pitchblende is the mineral associated with the fuel used in nuclear power stations.
Uranium is extracted and processed from uranium ores like pitchblende (Uraninite) to produce fuel rods for nuclear reactors. The specific isotope used for fission is Uranium-235.

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40. The correct sequence of energy transfer that occurs when an apple fall

The correct sequence of energy transfer that occurs when an apple falls to the ground is

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Gravitational potential energy $ o$ heat energy to air $ o$ kinetic energy $ o$ heat energy to ground and apple $ o$ sound energy
Gravitational potential energy $ o$ sound energy $ o$ heat energy to air $ o$ heat energy to ground and apple
Gravitational potential energy $ o$ kinetic energy $ o$ heat energy to air $ o$ heat energy to apple $ o$ sound energy
Gravitational potential energy $ o$ kinetic energy $ o$ sound energy $ o$ heat energy to air $ o$ heat energy to ground and apple
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The correct answer is C) Gravitational potential energy $\to$ kinetic energy $\to$ heat energy to air $\to$ heat energy to apple $\to$ sound energy.
When an apple falls, its initial gravitational potential energy is converted into kinetic energy. As the apple falls, air resistance acts on it, converting some of the kinetic energy into heat energy transferred to the surrounding air. Upon hitting the ground, the remaining kinetic energy is rapidly converted into sound energy (the impact sound) and heat energy due to the deformation and friction of the apple and the ground. Option C correctly shows the initial conversion from GPE to KE, followed by the dissipation of energy from KE into heat (to air and apple/ground) and sound upon impact. While heat to air occurs *during* the fall and sound/impact heat occurs *at the end*, option C provides the most plausible sequence among the choices, suggesting that the kinetic energy is the source from which heat to air, heat to apple, and sound energy arise.
Energy transformation during a fall is a classic example of the conservation of energy principle, where potential energy is converted into other forms. In realistic scenarios, dissipative forces like air resistance and the inelastic nature of collisions convert mechanical energy (potential and kinetic) into non-mechanical forms like heat and sound. The order in the options is not strictly temporal for the final dissipation forms, but C best represents the conversion path from potential to kinetic, and then the subsequent forms derived from kinetic energy.

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