TGPSC Group-I Prelims 1990

131 questions from the 1990 papers, each with the official answer and an explanation.

A question repeated across years is listed once, under one of the years it appeared.

81. Q81Structure of Indian society

    Africans are.

    • aindigenous people of South AfricaAnswer
    • bwhite people who emerged due to apartheid
    • ca terrorist organization of black people
    • dNone of these
    ›Explanation

    Option A is correct because in the context of South African racial classification and history, native Black Africans constitute the indigenous African population of South Africa. Option B: White people in South Africa are primarily descendants of European settlers (Afrikaners/Boers and British), not Africans who emerged due to apartheid. Option C: Africans are a vast racial and ethnic population, not a terrorist organization. Option D: An accurate definition is present in Option A.

82. Q82Social movements after independence

    The call for Jharkhand State is for establishing a

    • aSmall State
    • bHindi speaking state
    • cTribal StateAnswer
    • dNone of the above
    ›Explanation

    Option C is correct because the demand for the creation of Jharkhand historically emerged as a movement for a distinct tribal homeland to protect the cultural identity, land, and autonomy of the Adivasi communities of the Chota Nagpur and Santhal Parganas regions. Option A: Small State represents a general administrative concept rather than the primary ethnic and cultural basis of the Jharkhand movement. Option B: Hindi speaking state misidentifies the linguistic basis, as the core population spoke diverse tribal languages like Santhali, Mundari, Ho, and regional dialects rather than demanding a Hindi linguistic state. Option D: None of the above is incorrect because the movement was explicitly centered on tribal identity.

83. Q83Space technology

    The Indian - made remote sensing satellite IRS - 1A was launched from

    • aThumba
    • bNevada
    • cBaiknourAnswer
    • dKalpakam
    ›Explanation

    Option C is correct because IRS-1A, India's first operational remote sensing satellite, was launched on 17 March 1988 using a Soviet Vostok launch vehicle from the Baikonur Cosmodrome. Option A: Thumba was utilized for suborbital sounding rocket launches and lacked orbital launch facilities. Option B: Nevada has no orbital launch complex used by ISRO for space missions. Option D: Kalpakkam is a nuclear power and research facility in Tamil Nadu, not a rocket launching station.

84. Q84Space technology

    One of the purpose of INSAT 1D, the satellite put up by Indian Scientist, is to link all parts of India by television. The height about the earth surface at which it is revolving is about

    • a200 km
    • b10,000 km
    • c36,000 kmAnswer
    • d1, 00,000 km
    ›Explanation

    Option C is correct because INSAT 1D is a geostationary satellite, and all geostationary communication satellites revolve at an altitude of approximately 35,786 km (roughly 36,000 km) above the Earth's equator. Option A: 200 km is typical for low Earth orbit, where satellites have an orbital period of about 90 minutes rather than matching Earth's rotation. Option B: 10,000 km represents medium Earth orbit, which is not geosynchronous. Option D: 1,00,000 km is far out in deep space beyond operational satellite orbits.

85. Q85Space technology

    GRAMSAT is

    • astrengthens Panchayat Raj institutionsAnswer
    • bpromotes village courts
    • cpromotes rural industries
    • dpromotes the spread of literacy in India
    ›Explanation

    Option A is correct because the GRAMSAT pilot program was initiated by ISRO to provide dedicated satellite communications networks to rural areas, primarily designed to assist and strengthen grassroots governance and Panchayati Raj institutions through e-governance, training, and development communications. Option B: Village courts or Gram Nyayalayas are established under a statutory judicial framework rather than the technical mandate of the GRAMSAT initiative. Option C: Promoting rural industries is the domain of initiatives managed by ministries like MSME and rural development agencies, not the core objective of GRAMSAT. Option D: While distance learning can be supported via satellite, GRAMSAT's core objective focuses on rural development and grassroots governance, whereas widespread literacy was primarily addressed through missions like EDUSAT and national literacy missions.

86. Q86Nuclear technology

    The main element which releases the energy in the thermal reactor is

    • aUranium (235)Answer
    • bUranium (238)
    • cUranium (233)
    • dPlutonium (239)
    ›Explanation

    Option A is correct because Uranium-235 is the only naturally occurring fissile isotope capable of readily undergoing nuclear fission when struck by low-energy thermal neutrons in a thermal reactor. Option B: Uranium-238 is fertile and undergoes fission only with high-energy fast neutrons, primarily serving as breeding material rather than the primary thermal energy source. Option C: Uranium-233 is a synthetic fissile isotope derived from Thorium, not the main fuel constituent of standard commercial thermal reactors. Option D: Plutonium-239 is primarily bred in fast breeder reactors or utilised in specialised mixed-oxide fuels, rather than being the original main energy-releasing element of standard thermal reactors.

87. Q87SCHOOL BIOLOGY: life sciences as the papers actually ask them

    In living organisms the water acts as

    • aDiluting agent
    • bPhysiological solventAnswer
    • cLowers body temperature
    • dNone of the above
    ›Explanation

    Option B is correct because water is dipolar and possesses a high dielectric constant, enabling it to act as the primary physiological solvent that dissolves metabolites and facilitates biochemical reactions in cells. Option A: Describing water merely as a diluting agent overlooks its essential role as an active chemical and metabolic medium in biological systems. Option C: Water buffers and stabilizes body temperature through its high specific heat capacity and heat of vaporization, rather than solely lowering it. Option D: Erroneously rejects Option B, which correctly states the universally recognized biochemical role of water.

88. Q88SCHOOL BIOLOGY: life sciences as the papers actually ask them

    Hormone that helps in cell division

    • aAbscisic acid
    • bCytokininAnswer
    • cGibberellic acid
    • dRenin
    ›Explanation

    Option B is correct because cytokinins are plant growth hormones that actively promote cytokinesis, which is the process of cell division, primarily in root tips and developing shoots. Option A: Abscisic acid is a growth inhibitor that promotes dormancy and stomatal closure. Option C: Gibberellic acid primarily stimulates stem elongation and seed germination. Option D: Renin is an enzyme secreted by animal kidneys, not a plant hormone.

89. Q89SCHOOL BIOLOGY: life sciences as the papers actually ask them

    Plants stop both respiration and photosynthesis sometimes during

    • aNight
    • bTwilightAnswer
    • cDaytime
    • dDawn
    ›Explanation

    Option B is correct because during twilight, plants reach the light compensation point where the rates of photosynthesis and respiration equal each other, leading to zero net exchange of carbon dioxide and oxygen. Option A: Respiration continues actively throughout the night even though photosynthesis stops in darkness. Option C: Both photosynthesis and respiration occur at high rates during the day with substantial net gaseous exchange. Option D: Dawn represents only the morning transition, whereas twilight encompasses both dawn and dusk compensation periods.

90. Q90SCHOOL BIOLOGY: life sciences as the papers actually ask them

    Rate of transpiration is the maximum when there is

    • alow temperature
    • blow wind velocity
    • chigh temperature and low humidityAnswer
    • dhigh humidity
    ›Explanation

    Option C is correct because higher temperatures provide the thermal energy needed for water evaporation, while low humidity steepens the water-vapour concentration gradient between the leaf interior and the ambient atmosphere, accelerating transpiration. Option A: Low temperature reduces the kinetic energy of water molecules and lowers the evaporation rate. Option B: Low wind velocity allows humid air to stagnate near stomata, reducing the vapor pressure deficit and slowing transpiration. Option D: High humidity saturates the surrounding air, which reduces the moisture gradient and impedes transpiration.

91. Q91SCHOOL BIOLOGY: life sciences as the papers actually ask them

    Hybrid varieties of seeds are

    • abreed from two plants of different varietiesAnswer
    • balways high yielding
    • cbreed from transplantation
    • dvulnerable to disease
    ›Explanation

    Option A is correct because hybrid seeds are produced by intentionally cross-pollinating two genetically distinct parent varieties to combine their advantageous traits. Option B: Hybrids are not guaranteed to be high yielding, as their productivity depends on growing conditions and proper management. Option C: Hybridization is a genetic breeding method rather than an agronomic practice like transplantation. Option D: Many hybrid varieties are specifically bred for enhanced pest and disease resistance rather than being inherently vulnerable.

92. Q92SCHOOL BIOLOGY: life sciences as the papers actually ask them

    The most intelligent animal is

    • aMonkey
    • bManAnswer
    • cChimpanzee
    • dBird
    ›Explanation

    Option B is correct because Homo sapiens (Man) possesses the most developed cerebral cortex and the highest cognitive and intellectual capabilities among all animals. Option A: Monkey possesses lower cognitive and reasoning abilities compared to man. Option C: Chimpanzee is one of the closest non-human relatives to humans, but its intelligence is far surpassed by man. Option D: Bird exhibits certain intelligent behaviors like tool-use in some species, but ranks far below man.

93. Q93HUMAN BODY, NUTRITION AND DISEASE

    In the human body fats are stored in

    • aepithelial cells
    • badipose tissueAnswer
    • cepidermis
    • dliver
    ›Explanation

    Option B is correct because adipose tissue is a specialized loose connective tissue containing adipocytes that synthesize and store energy in the form of neutral triglycerides. Option A: Epithelial cells form protective linings and coverings across internal and external body surfaces, not primary fat storage. Option C: Epidermis is the outermost cellular layer of the skin composed of keratinocytes, lacking bulk fat storage capacity. Option D: Liver metabolizes lipids and can hold transient fat, but it is an organ whose primary role is not the principal fat-storage depot.

94. Q94HUMAN BODY, NUTRITION AND DISEASE

    Which part of the human brain controls sneezing ?

    • aCerebrum
    • bMedulla oblongataAnswer
    • cHypothalamus
    • dNone of the above
    ›Explanation

    Option B is correct because the sneeze centre is located within the medulla oblongata of the brainstem, which coordinates the involuntary reflex arc triggering deep inspiration followed by forceful expiration. Option A: Cerebrum coordinates conscious thought, perception, and voluntary movement rather than autonomic sneeze reflexes. Option C: Hypothalamus regulates neuroendocrine function and homeostatic drives such as hunger and body temperature, not the sneeze reflex. Option D: None of the above is incorrect because the medulla oblongata directly controls this reflex.

95. Q95HUMAN BODY, NUTRITION AND DISEASE

    The ductless glands in the human body which secrete hormones are called

    • aexocrine glands
    • bendocrine glandsAnswer
    • cepithelial glands
    • dmetabolic glands
    ›Explanation

    Option B is correct because endocrine glands are ductless glands that secrete chemical messengers called hormones straight into the bloodstream or interstitial fluid. Option A: Exocrine glands possess ducts to transport their non-hormonal secretions to external or internal epithelial surfaces. Option C: Epithelial glands refers to the tissue type forming secretory units, which includes both duct-bearing and ductless varieties. Option D: Metabolic glands is not an established anatomical classification for glands in the human body.

96. Q96HUMAN BODY, NUTRITION AND DISEASE

    The richest vegetabe source of Vitamin A

    • aLiver
    • bEgg
    • cCarrotAnswer
    • dSunlight
    ›Explanation

    Option C is correct because carrot is among the richest plant sources of beta-carotene, a provitamin A carotenoid that the human body converts into active Vitamin A (retinol). Option A: Liver is an animal organ source, not a vegetable source. Option B: Egg is an animal product, not a vegetable source. Option D: Sunlight stimulates the synthesis of Vitamin D in the skin and is neither a food source nor related to Vitamin A production.

97. Q97HUMAN BODY, NUTRITION AND DISEASE

    Rickets is caused by the deficiency of

    • aVitamin C
    • bProtein
    • cIodine
    • dVitamin DAnswer
    ›Explanation

    Option D is correct because Vitamin D deficiency hinders the intestinal absorption of calcium and phosphate, leading to inadequate mineralization of bone tissue in children, which causes the skeletal softening and deformities characteristic of rickets. Option A: Vitamin C deficiency impairs collagen synthesis, resulting in scurvy rather than rickets. Option B: Severe dietary protein deficiency in children causes kwashiorkor or marasmus, which are wasting syndromes rather than rickets. Option C: Iodine deficiency prevents normal thyroid hormone production, leading to goitre and cretinism rather than rickets.

98. Q98HUMAN BODY, NUTRITION AND DISEASE

    Which of the following is most important for the growth of children up to the age of 14?

    • aProteinAnswer
    • bVitamins
    • cFat
    • dMilk
    ›Explanation

    Option A is correct because proteins supply essential amino acids that serve as the primary structural building blocks required for rapid cell proliferation, muscle development, and organ formation in children up to age 14. Option B: vitamins act as micronutrients and coenzymes for metabolic reactions, not as structural building material for bodily growth. Option C: fat primarily provides energy reserves and cellular insulation rather than direct structural growth. Option D: milk is an unrefined food item containing various nutrients, whereas protein is the specific fundamental nutrient responsible for tissue synthesis.

99. Q99HUMAN BODY, NUTRITION AND DISEASE

    In an oxygen tube, which of the following gases is preferred these days to be mixed with oxygen ?

    • anitrogen
    • bheliumAnswer
    • cargon
    • dcarbon dioxide
    ›Explanation

    Option B is correct because helium mixed with oxygen, known as heliox, is preferred in deep-sea diving and respiratory therapy because helium has low blood solubility and low density, which prevents nitrogen narcosis and the bends while reducing breathing resistance. Option A: Nitrogen dissolves in blood under high ambient pressure, causing decompression sickness and nitrogen narcosis, making it less suitable than helium. Option C: Argon has high narcotic potency and higher density, making breathing under pressure difficult. Option D: Carbon dioxide is a metabolic waste product that leads to respiratory acidosis and hypercapnia, making it unsafe to mix as a carrier gas.

100. Q100SCHOOL CHEMISTRY

     Which element has the same atomic number and atomic weight ?

     • aOxygen
     • bNitrogen
     • cHelium
     • dHydrogenAnswer
     ›Explanation

     Option D is correct because the most abundant isotope of hydrogen, protium, contains one proton and no neutrons in its nucleus, making both its atomic number and atomic mass number equal to 1. Hydrogen atomic number: 1 Hydrogen mass number: 1 Helium atomic number: 2, mass number: 4 Nitrogen atomic number: 7, mass number: 14 Oxygen atomic number: 8, mass number: 16 Option A: Oxygen has an atomic number of 8 and a mass number of 16. Option B: Nitrogen has an atomic number of 7 and a mass number of 14. Option C: Helium has an atomic number of 2 and a mass number of 4.

101. Q101SCHOOL CHEMISTRY

     Diamond and emerald are made of

     • aCarbon
     • bSilica
     • cSilica and Beryllium
     • dCarbon and berylliumAnswer
     ›Explanation

     Option D is correct because diamond is a crystalline allotrope composed entirely of carbon, whereas emerald is a green gemstone variety of beryl, a mineral whose chemical makeup prominently features beryllium. Option A: Carbon constitutes diamond alone, whereas emerald contains beryllium along with aluminium, silicon, and oxygen. Option B: Silica forms quartz and various silicate minerals, but diamond contains no silicon or oxygen. Option C: Silica and beryllium describe constituent elements of emerald, but this option entirely omits the carbon that constitutes diamond.

102. Q102SCHOOL CHEMISTRY

     One of the constituents of Gobar gas is

     • aMethaneAnswer
     • bEthane
     • cCarbon dioxide
     • dCalcium sulphate
     ›Explanation

     Option A is correct because methane is the primary combustible constituent of gobar gas, making up 55 to 70 percent of the gas produced through the anaerobic digestion of animal dung. Option B: Ethane is a minor component found in fossil natural gas, not a significant constituent of biogenic gobar gas. Option C: Carbon dioxide is an inert byproduct present in biogas, but methane is the principal fuel constituent highlighted in standard syllabi. Option D: Calcium sulphate is an inorganic solid salt and is not a gaseous component produced during anaerobic fermentation.

103. Q103SCHOOL PHYSICS

     Two different objects with masses m1 and m2 are projected in the air at the angles q1 and q2 with respect to horizontal direction with the speed v1 and v2. If they remain in air for the same amount of time, the following quantity must be the same.

     • amass
     • bspeed
     • cthe distance travelled in horizonal direction
     • dthe height attainedAnswer
     ›Explanation

     Option D is correct because the total time of flight of a projectile depends exclusively on the vertical component of its initial velocity, and that same vertical component determines the maximum vertical height attained. Time of flight: T = 2 * u_y / g Maximum height: H = (u_y)^2 / (2 * g) Height in terms of time: H = g * T^2 / 8 Option A: Mass does not appear in the kinematic equations for projectile motion under gravity. Option B: The overall speed depends on both horizontal and vertical components, so identical flight times do not require identical initial speeds. Option C: The horizontal distance traveled depends on the horizontal velocity component, which is independent of the time of flight.

104. Q104SCHOOL PHYSICS

     At what temperature is the density of the water highest ?

     • a0° C
     • b4°CAnswer
     • c20°C
     • d100°C
     ›Explanation

     Option B is correct because water exhibits anomalous expansion between 0°C and 4°C, reaching its maximum density and minimum volume at 4°C. Option A: At 0°C, water forms an open hexagonal crystal lattice, making its density lower than at 4°C. Option C: At 20°C, normal thermal expansion causes water molecules to move farther apart, resulting in lower density than at 4°C. Option D: At 100°C, extensive thermal expansion significantly lowers the density of water compared to its value at 4°C.

105. Q105SCHOOL PHYSICS

     Radio and TV reproduce the programme after receiving the waves by antenna. These waves are

     • anothing but Mght rays but with larger frequency
     • bnothing but light rays but with larger wavelengthAnswer
     • clike soundwaves with higher frequencies
     • dnone of the above
     ›Explanation

     Option B is correct because radio and TV waves are electromagnetic radiations identical in nature to light rays, but they possess much longer wavelengths and lower frequencies than visible light. Option A: Radio and TV waves operate at significantly lower frequencies than visible light, not larger ones. Option C: Sound waves are mechanical longitudinal waves requiring a material medium, whereas radio waves are electromagnetic transverse waves. Option D: Option B correctly identifies the electromagnetic nature and wave properties of these signals.

106. Q106SCHOOL PHYSICS

     Due to which property of the light waves, the solar and lunar eclipse take place ?

     • aInterference
     • bDiffraction
     • cPolarisation
     • dRectilinear propagationAnswer
     ›Explanation

     Option D is correct because rectilinear propagation describes light traveling in straight lines, which causes opaque celestial bodies like the Earth and Moon to cast sharp shadows, leading to lunar and solar eclipses. Option A: Interference involves the overlapping of waves to form light and dark bands, not the casting of planetary shadows. Option B: Diffraction involves waves bending around edges, which is negligible at macro scales and does not cause eclipses. Option C: Polarisation is the restriction of wave vibrations to a single plane, which has no role in shadow formation.

107. Q107SCHOOL PHYSICS

     Which of the following gives the proper order of colours ?

     • ared, green, blueAnswer
     • bblue, green, red
     • cblue, green, yellow
     • dblue, yellow, green

     Official answer shown. The explanation is under review.

108. Q108SCHOOL PHYSICS

     The interaction which governs the life every where is

     • aElectromagneticAnswer
     • bGravitation
     • cNuclear
     • dWeak
     ›Explanation

     Option A is correct because life processes at molecular, cellular, and physiological levels are governed by electromagnetic interactions, which dictate chemical bonds, enzyme-substrate actions, and nerve impulses. Option B: Gravitation is wrong because gravity is far too weak to govern biological reactions and molecular-scale cellular activities. Option C: Nuclear is wrong because strong and weak nuclear forces operate strictly over subatomic distances inside atomic nuclei. Option D: Weak is wrong because weak interactions primarily mediate beta decay processes and do not direct biological chemistry.

109. Q109Logical reasoning and analytical ability

     Arrange the following in a meaningful sequence 1) Story 2) Review 3) Book 4) Idea 5) Author

     • a1-2-4-5-3
     • b4-1-3-2-5
     • c5-4-1-3-2Answer
     • d3-2-4-1-5
     ›Explanation

     Option C is correct because the sequence reflects the natural creative and publishing process where an author conceives an idea, drafts a story, publishes it as a book, and finally receives a review. Author Idea Story Book Review Option A: places the story and review before the author and idea, reversing the order of creation. Option B: places the author at the very end, whereas the author must originate the concept. Option D: starts with the finished book and review before an idea is even conceived.

110. Q110Series, analogy and odd man out

     Complete the series by choosing the correct answer out of one of the four choices given below in questions 92 to 95 : 92. 3,9,21,45,?

     • a90
     • b93Answer
     • c92
     • d91
     ›Explanation

     Option B is correct because the series increases by doubling the difference added at each step, or each term is obtained by multiplying the previous term by 2 and adding 3. 3 x 2 + 3 = 9 9 x 2 + 3 = 21 21 x 2 + 3 = 45 45 x 2 + 3 = 93 Option A: 90 is obtained by simply doubling 45 without adding the required constant. Option C: 92 is an arithmetic miscalculation that adds 47 instead of 48. Option D: 91 fails to follow the doubling progression of increments.

111. Q111Series, analogy and odd man out

     Complete this sequence A D H M --

     • aO & T
     • bN & S
     • cS & ZAnswer
     • dU & Y
     ›Explanation

     Option C is correct because the gap between consecutive letters increases successively by one. A (1) + 3 = D (4) D (4) + 4 = H (8) H (8) + 5 = M (13) M (13) + 6 = S (19) S (19) + 7 = Z (26) Option A: O and T result from adding 2 and 5 respectively, which deviates from the incrementing difference pattern. Option B: N and S result from adding 1 and 5 respectively, ignoring the progressive addition. Option D: U and Y correspond to positions 21 and 25, failing the +6 and +7 pattern.

112. Q112Series, analogy and odd man out

     Complete this sequence T W A C -

     • aE
     • bFAnswer
     • cH
     • dI
     ›Explanation

     Option B is correct because the sequence follows an alternating addition pattern across the alphabet. T is letter 20, and adding 3 gives W (23) W (23) plus 4 gives A (27 or 1) A (1) plus 2 gives C (3) C (3) plus 3 gives F (6) Option A: E corresponds to adding 2 instead of 3 to C. Option C: H corresponds to adding 5 to C, breaking the sequence. Option D: I corresponds to adding 6 to C, which is incorrect.

113. Q113Series, analogy and odd man out

     Indicate the Word/Number / Alphabet which DOES NOT belong to the same class or series in Questions 98 and 99 : 98. Square, Rectangle, Circle, Triangle

     • aSquare
     • bRectangle
     • cCircleAnswer
     • dTriangle
     ›Explanation

     Option C is correct because a circle is a curved, non-rectilinear figure with no straight edges or vertices, whereas all the other options are polygons made of straight line segments. Option A: A square is a polygon composed of straight sides and vertices. Option B: A rectangle is a polygon bounded by straight lines and vertices. Option D: A triangle is a polygon formed by three straight line segments.

114. Q114Coding, decoding and relations

     In a code BOMBAY is written as CPNCBZ; What is NBESBT then ?

     • aLONDON
     • bMADRASAnswer
     • cMADRID
     • dMYSORE
     ›Explanation

     Option B is correct because NBESBT is the coded form of the original word, derived by shifting each letter backward by one position. N minus 1 gives M B minus 1 gives A E minus 1 gives D S minus 1 gives R B minus 1 gives A T minus 1 gives S Option A: LONDON has letters that do not precede the letters of NBESBT alphabetically. Option C: MADRID ends in ID, which would code to JE rather than BT. Option D: MYSORE contains six letters whose forward shifted code would completely differ from NBESBT.

115. Q115Coding, decoding and relations

     WISE is coded as XKVI, TALK will be coded

     • aUCON
     • bVCON
     • cUCOÒAnswer
     • dUCOP
     ›Explanation

     Option C is correct because each letter in the word is shifted forward by an increasing number of positions (+1, +2, +3, +4), and applying this rule to TALK gives UCOO, which is printed with a diacritic as UCOÒ in the examination paper. T + 1 = U A + 2 = C L + 3 = O K + 4 = O Option A: gives N as the final letter instead of O. Option B: gives V as the first letter instead of U and N as the final letter. Option D: gives P as the final letter instead of O.

116. Q116Coding, decoding and relations

     LATE is written as GWQC; POUR will be written as

     • aKJRP
     • bKKRQ
     • cKJPR
     • dKKRPAnswer
     ›Explanation

     Option D is correct because the letters are shifted backward by decreasing values of 5, 4, 3, and 2 respectively. P minus 5 gives K O minus 4 gives K U minus 3 gives R R minus 2 gives P Option A: KJRP incorrectly subtracts five from O instead of four. Option B: KKRQ subtracts one from R instead of two. Option C: KJPR incorrectly subtracts five from O and swaps the final two letters.

117. Q117Coding, decoding and relations

     Y is brother of Z. A is the daughter of Z. U is the sister of Y and B is the brother of A. Who is the uncle of B ?

     • aYAnswer
     • bU
     • cZ
     • dA
     ›Explanation

     Option A is correct because A and B are siblings and children of Z. Y is the brother of Z, which makes Y the paternal uncle of both A and B. Option B: U is the sister of Z and Y, making U an aunt rather than an uncle. Option C: Z is the parent of B, not the uncle. Option D: A is the sister of B, not his uncle.

118. Q118Number system and basic operations

     Which fraction lies between 2 / 3 and 4 / 5 ?

     • a17/20
     • b7/10Answer
     • c13/15
     • d4/9
     ›Explanation

     Option B is correct because 7/10 equals 0.70, which lies strictly between 2/3 (approximately 0.667) and 4/5 (0.80). 2/3 = 0.666... 4/5 = 0.800 7/10 = 0.700 Option A: 17/20 equals 0.85, which is strictly greater than 4/5. Option C: 13/15 equals approximately 0.867, which exceeds 4/5. Option D: 4/9 equals approximately 0.444, which is strictly less than 2/3.

119. Q119Number system and basic operations

     If + is multiplication, - is addition, x is division and, is subtraction, which of the following is correct ?

     • a10 4x2 = 4 + 6-2
     • b10 + 4-2 = 4x62
     • c10-4 2-4 + 6x2Answer
     • dNone of these

     Explanation coming soon.

120. Q120Number system and basic operations

     Which number replaces both the question marks in the following problem ? 8 / ? = ? / 200

     • a100
     • b400
     • c40Answer
     • d25
     ›Explanation

     Option C is correct because cross-multiplying the equation gives the square of the unknown equal to 1600, whose square root is 40. 8 / x = x / 200 x² = 8 * 200 x² = 1600 x = √1600 = 40 Option A: 100 squared is 10000, not 1600. Option B: 400 squared is 160000, not 1600. Option D: 25 squared is 625, not 1600.