Science & Technology

923 questions asked in UPSC Prelims.

1998 · Q126 Science & TechnologyChemistrymoderate

Match List I with List II and select the correct answer using the codes given below the lists: List I I. Blue vitriol II. Epsom salt III. Baking soda IV. Caustic soda List II A) Sodium bicarbonate B) Sodium hydroxide C) Magnesium sulphate D) Copper sulphate

(a)I-C, II-D, III-B, IV-A
(b)I-D, II-C, III-A, IV-B
(c)I-C, II-D, III-A, IV-B
(d)I-D, II-A, III-B, IV-A

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Official answer(b) I-D, II-C, III-A, IV-B

1998 · Q127 Science & TechnologyChemistrymoderate

Assertion (A): Formic acid is a stronger acid than acetic acid. Reason (R): Formic acid is an organic acid.

(a)Both A and R are true, and R is the correct explanation of A
(b)Both A and R are true, but R is NOT a correct explanation of A
(c)A is true, but R is false
(d)A is false, but R is true

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Official answer(b) Both A and R are true, but R is NOT a correct explanation of A

1998 · Q128 Science & TechnologyPhysicsmoderate

Assertion (A): The temperature of a metal wire rises when an electric current is passed through it. Reason (R): Collision of metal atoms with each other releases heat energy.

(a)Both A and R are true, and R is the correct explanation of A
(b)Both A and R are true, but R is NOT a correct explanation of A
(c)A is true, but R is false
(d)A is false, but R is true

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Official answer(c) A is true, but R is false

1998 · Q129 Science & TechnologyChemistryeasy

Assertion (A): Phenyl is used as a household germicide. Reason (R): Phenyl is a phenol derivative and phenol is an effective germicide.

(a)Both A and R are true, and R is the correct explanation of A
(b)Both A and R are true, but R is NOT a correct explanation of A
(c)A is true, but R is false
(d)A is false, but R is true

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Official answer(a) Both A and R are true, and R is the correct explanation of A

1998 · Q130 Science & TechnologyChemistryeasy

Assertion (A): Sodium metal is stored under kerosene. Reason (R): Metallic sodium melts when exposed to air.

(a)Both A and R are true, and R is the correct explanation of A
(b)Both A and R are true, but R is NOT a correct explanation of A
(c)A is true, but R is false
(d)A is false, but R is true

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Official answer(c) A is true, but R is false

1998 · Q133 Science & TechnologyQuantitative Aptitudemoderate

LMNOP is a semi-circle with centre at R and diameter LP; LSR and RQP are also semi-circles with centres at T and U and diameters LR = RP = 1⁄2 LP. The ratio of perimeters of LMNOP and LSRQP is

(a)0.75 : 1
(b)1 : 1
(c)1 : 0.75
(d)1.25 : 1

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Official answer(b) 1 : 1

1998 · Q134 Science & TechnologyQuantitative Aptitudemoderate

A man purchases two clocks A and B at a total cost of Rs 650. He sells A with 20% profit and B at a loss of 25% and gets the same selling price for both the clocks. What are the purchasing prices of A and B respectively?

(a)Rs 225; Rs 425
(b)Rs 250; Rs 400
(c)Rs 275; Rs 375
(d)Rs 300; Rs 350

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Official answer(b) Rs 250; Rs 400

1998 · Q135 Science & TechnologyQuantitative Aptitudeeasy

If 15 pumps of equal capacity can fill a tank in 7 days, then how many extra pumps will be required to fill the tank in 5 days?

(a)6
(b)7
(c)14
(d)21

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Official answer(a) 6

1998 · Q136 Science & TechnologyQuantitative Aptitudeeasy

Out of the three annual examinations, each with a total of 500 marks, a student secured average marks of 45 % and 55 % in the first and second annual examinations. To have an overall average of 60 %, how many marks does the student need to secure in the third annual examination?

(a)450
(b)400
(c)350
(d)300

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Official answer(b) 400

1998 · Q137 Science & TechnologyLogical Reasoning & Puzzlesmoderate

Which one of the following satisfies the relationship D d a : a D D :: R r b : ?

(a)D D A
(b)R R R
(c)b R R
(d)B B r

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Official answer(c) b R R

1998 · Q138 Science & TechnologyQuantitative Aptitudemoderate

A square pond has 2 m sides and is 1 m deep. If it is to be enlarged, the depth remaining the same, into a circular pond with the diagonal of the square as diameter as shown in the figure, then what would be the volume of earth to be removed?

(a)(2π − 4) m³
(b)(4π − 4) m³
(c)(4π − 2) m³
(d)(2π − 2) m³

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Official answer(a) (2π − 4) m³

1998 · Q139 Science & TechnologyQuantitative Aptitudeeasy

One local and another express train were proceeding in the same direction on parallel tracks at 29 km/hour and 65 km/hour respectively. The driver of the former noticed that it took exactly 16 seconds for the faster train to pass by him. What is the length of the faster train?

(a)60 m
(b)120 m
(c)160 m
(d)240 m

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Official answer(c) 160 m

1998 · Q140 Science & TechnologyLogical Reasoning & Puzzlesmoderate

A, B, C, D, E and F, not necessarily in that order, are sitting on six chairs regularly placed around a round table. It is observed that A is between D and F, C is opposite D, and D and E are not on neighbouring chairs. Which one of the following pairs must be sitting on neighbouring chairs?

(a)A and B
(b)C and E
(c)B and F
(d)A and C

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Official answer(b) C and E

1998 · Q141 Science & TechnologyLogical Reasoning & Puzzleseasy

If in a certain code SAND is VDQG and BIRD is ELUG, then what is the code for LOVE?

(a)PRYG
(b)ORTG
(c)NPUH
(d)ORYH

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Official answer(d) ORYH

1998 · Q142 Science & TechnologyQuantitative Aptitudemoderate

In a family, a couple has a son and a daughter. The age of the father is three times that of his daughter and the age of the son is half of his mother. The wife is nine years younger to her husband and the brother is seven years older than his sister. What is the age of the mother?

(a)40 years
(b)45 years
(c)50 years
(d)60 years

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Official answer(d) 60 years

1998 · Q143 Science & TechnologyLogical Reasoning & Puzzlesmoderate

The missing fraction in the series given below is:

(a)17/40
(b)19/42
(c)20/45
(d)29/5

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Official answer(b) 19/42

1998 · Q144 Science & TechnologyQuantitative Aptitudeeasy

There are 50 students admitted to a nursery class. Some students can speak only English and some can speak only Hindi. Ten students can speak both English and Hindi. If the number of students who can speak English is 21, then how many students can speak only Hindi and how many can speak only English?

(a)21, 11 and 29 respectively
(b)28, 18 and 22 respectively
(c)37, 27 and 13 respectively
(d)39, 29 and 11 respectively

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Official answer(d) 39, 29 and 11 respectively

1998 · Q145 Science & TechnologyQuantitative Aptitudeeasy

An accurate clock shows the time as 3 : 00. After the hour hand has moved 135°, the time would be

(a)7 : 30
(b)6 : 30
(c)8 : 00
(d)9 : 30

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Official answer(a) 7 : 30

1998 · Q147 Science & TechnologyLogical Reasoning & Puzzlesmoderate

In the set of figures (I) to (IV), some parts are shown to change their position in a regular direction. Following the same sequence, which one of the following will appear at the fifth stage?

(a)figure (a)
(b)figure (b)
(c)figure (c)
(d)figure (d)

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Official answer(c) figure (c)

1998 · Q148 Science & TechnologyLogical Reasoning & Puzzlesmoderate

Examine the following statements: I. All members of Mohan’s family are honest. II. Some members of Mohan’s family are not employed. III. Some employed persons are not honest. IV. Some honest persons are not employed. Which of the following inferences can be drawn from the above statements?

(a)All members of Mohan’s family are employed
(b)The employed members of Mohan’s family are honest
(c)The honest members of Mohan’s family are not employed
(d)The employed members of Mohan’s family are not honest

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Official answer(b) The employed members of Mohan’s family are honest

1998 · Q149 Science & TechnologyLogical Reasoning & Puzzlesmoderate

In a dinner party both fish and meat were served. Some took only fish and some only meat. There were some vegetarians who did not accept either. The rest accepted both fish and meat. Which one of the following logic diagrams correctly reflects the above situation?

(a)diagram (a)
(b)diagram (b)
(c)diagram (c)
(d)diagram (d)

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Official answer(a) diagram (a)

1998 · Q150 Science & TechnologyLogical Reasoning & Puzzlesmoderate

A, B, C, D, E, F and G are members of a family consisting of 4 adults and 3 children, two of whom, F and G, are girls. A and D are brothers and A is a doctor. E is an engineer married to one of the brothers and has two children. B is married to D and G is their child. Who is C?

(a)G’s brother
(b)F’s father
(c)E’s daughter
(d)A’s son

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Official answer(a) G’s brother

1997 · Q13 Science & TechnologySpace Technology & Astronomyeasy

The tail of a comet is directed away from the sun because

(a)as the comet rotates around the sun, the lighter mass of the comet is pushed away due to the centrifugal force alone
(b)as the comet rotates, the lighter mass of the comet is attracted by some star situated in the direction of its tail
(c)the radiation emitted by the sun exerts a radial pressure on the comet throwing its tail away from the sun
(d)the tail of the comet always exists in the same orientation

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Official answer(c) the radiation emitted by the sun exerts a radial pressure on the comet throwing its tail away from the sun

1997 · Q27 Science & TechnologyChemistryeasy

Which one of the following was used as a chemical weapon in the First World War?

(a)Carbon monoxide
(b)Hydrogen cyanide
(c)Mustard gas
(d)Water gas

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Official answer(c) Mustard gas

1997 · Q40 Science & TechnologyComputer & Information Technologyeasy

The world’s fastest computer has been able to perform (as of Dec. 1996)

(a)106 operations per second
(b)109 operations per second
(c)1012 operations per second
(d)1015 operations per second

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Official answer(c) 1012 operations per second