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General Science Previous Year Questions (PYQ) with Answers – Page 5

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General Science questions asked in previous year papers of SSC, Banking, Railway and other exams, with the exam and year, answers and explanations.

1911 previous-year questions

All General Science questionsGeneral Science NotesPYQs by exam
Q81.General ScienceAsked in: NDA · NDA-II 2026, GATHard

Consider the following statements regarding oxidation numbers : I. The oxidation number of oxygen in peroxides and superoxides is assigned as -1 and -1/2 respectively. II. In all its compounds, fluorine has an oxidation number of -1. III. In a reduction half-reaction, the oxidation number of the reductant decreases. Which of the statements given above are correct?

  1. A.I and II only
  2. B.II and III only
  3. C.I and III only
  4. D.I, II and III
Show answer
Correct answer: A. I and II only

Statements I and II are standard rules for oxidation numbers, but Statement III reverses what happens to a reducing agent.

Q82.General ScienceAsked in: NDA · NDA-I 2026, GATEasy

A non-volatile solid solute may be separated from a solution by which of the following processes? I. Evaporation II. Crystallization Select the correct answer using the code given below.

  1. A.I only
  2. B.II only
  3. C.Both I and II
  4. D.Neither I nor II
Show answer
Correct answer: C. Both I and II

A solid that does not vaporise stays behind when the solvent is removed, whether the solvent is boiled off or the solid is made to crystallise out.

Q83.General ScienceAsked in: NDA · NDA-II 2026, GATMedium

Consider the following statements : Statement-I : Marine animals remain alive in winter and move near the bottom of lakes despite frozen water on the surface. Statement-II : The density of water is maximum at 4°C and water at the bottom of lakes remains warm in winter. Which one of the following is correct in respect of the above statements?

  1. A.Both Statement-I and Statement-II are correct and Statement-II explains Statement-I.
  2. B.Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I.
  3. C.Statement-I is correct, but Statement-II is not correct.
  4. D.Statement-I is not correct, but Statement-II is correct.
Show answer
Correct answer: A. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I.

Because water is densest at 4°C, the bottom of a lake stays liquid and relatively warm while the surface freezes, so aquatic animals survive there.

Q84.General ScienceAsked in: CDS · CDS-I 2026, GKHard

Which of the following statements relating to the Modern Periodic Table is/are correct ?

1. The atomic radius increases on moving from left to right across a period.

2. Germanium, Tellurium, and Copper are transition metals.

3. The two isotopes of Chlorine occupy the same position in the periodic table.

4. The metallic property of Ca, Ba, Be and Sr follows the order : Be < Ca < Sr < Ba.

Select the answer using the codes given below :

  1. A.3 only
  2. B.1 and 4
  3. C.2 and 3
  4. D.3 and 4
Show answer
Correct answer: D. 3 and 4

Only statements 3 and 4 are true; statements 1 and 2 are false. The modern periodic table arranges elements by atomic number.

Q85.General ScienceAsked in: NDA · NDA-I 2026, GATHard

Consider the following statements : I. A colloid and a suspension are heterogeneous mixtures. II. Colloids can be separated from the mixture by the process of centrifugation. III. Particles of colloids and suspensions can be seen by naked eye. IV. The aqueous solution of copper sulphate does not show Tyndall effect; however, the mixture of milk and water shows Tyndall effect. Which of the statements given above is/are correct?

  1. A.I only
  2. B.II and III only
  3. C.I, II and III
  4. D.I, II and IV
Show answer
Correct answer: D. I, II and IV

Only statement III is wrong, because colloidal particles are too small to be seen with the naked eye. Mixtures are graded by particle size.

Q86.General ScienceAsked in: NDA · NDA-II 2026, GATMedium

Consider the following statements in respect of sound waves : I. The speed of sound waves decreases with an increase in temperature if the atmospheric pressure remains the same. II. The speed of sound waves increases with increasing humidity if the atmospheric pressure remains the same. III. The speed of sound waves is not affected by a change in atmospheric pressure, provided the temperature is kept constant. Which of the statements given above are correct?

  1. A.I and II only
  2. B.II and III only
  3. C.I and III only
  4. D.I, II and III
Show answer
Correct answer: B. II and III only

Sound travels faster in warmer air, so statement I is wrong, while II and III are right. The speed of sound in a gas is v = √(γP/ρ).

Q88.General ScienceAsked in: NDA · NDA-II 2026, GATHard

Consider three wires X, Y and Z of the same length such that the ratio of their conductivities is 1 : 2 : 3. Further, the cross-sectional area of wire Z is twice that of Y and the resistance of X is equal to the resistance of Z. What is the ratio of the resistance of Y to that of X?

  1. A.1 : 1
  2. B.3 : 1
  3. C.2 : 1
  4. D.1 : 2
Show answer
Correct answer: B. 3 : 1

Using R = L/(σA) with equal lengths, the resistance of Y comes out three times that of X. Resistance falls as conductivity σ and cross-sectional area A rise.

Q89.General ScienceAsked in: UPSC CAPF · CAPF 2026, Paper IEasy

The brightness of a lightning event was seen at 19:06:17 hr, whereas the sound of the thunder in the same process was heard at 19:06:23 hr. If the speed of the sound is 320 metres per second, then which of the following is the distance in metres between the clouds that produced the lightning and the thunder, and the observer?

  1. A.1720
  2. B.1820
  3. C.1920
  4. D.2020
Show answer
Correct answer: C. 1920

The thunder arrived 6 seconds after the flash, and sound covers 320 m every second, so the distance is 320 × 6 = 1920 m. Lightning and thunder are produced at the same moment.

Q90.General ScienceAsked in: CDS · CDS-I 2026, GKMedium

Consider the following statements : 1. The temporary hardness in water is due to the presence of bicarbonates of calcium. 2. The permanent hardness in water is due to the presence of soluble chlorides and sulphates of calcium and magnesium. 3. The permanent hardness in water is removed by adding Na₂CO₃ to water. Which of the statements given above are correct?

  1. A.1 and 2 only
  2. B.2 and 3 only
  3. C.1 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: D. 1, 2 and 3

All three statements describe hard water correctly. Statement 1 is correct: temporary hardness comes from dissolved bicarbonates, chiefly calcium bicarbonate (magnesium bicarbonate too).

Q92.General ScienceAsked in: NDA · NDA-II 2026, GATHard

An insulating container contains 250 g of water at 20°C. Steam at 100°C is passed through it, heating it up to 25°C. During this process, part of the steam also gets condensed, raising the mass of water to 252 g. If the specific heat of water is 1 Cal g⁻¹ °C⁻¹, then what is the value of the latent heat of steam?

  1. A.530 Cal/g
  2. B.540 Cal/g
  3. C.550 Cal/g
  4. D.560 Cal/g
Show answer
Correct answer: C. 550 Cal/g

The heat given out by 2 g of steam equals the heat taken in by 250 g of water, and that balance gives L = 550 Cal/g. The water warms from 20°C to 25°C, so it absorbs 250 × 1 × 5 = 1250 Cal.

Q93.General ScienceAsked in: CDS · CDS-I 2026, GKMedium

Consider the following statements : 1. Packaged foods are purged with nitrogen gas in order to prevent their oxidation. 2. Tooth decay starts when pH of the mouth is lower than 5.5. 3. The reactivity of metals decreases in the order : Mg > Fe > Zn. Which of the statements given above is/are not correct ?

  1. A.2 and 3
  2. B.1 and 3
  3. C.1 and 2
  4. D.3 only
Show answer
Correct answer: D. 3 only

Statements 1 and 2 are correct; statement 3 is wrong because zinc is more reactive than iron.

Q94.General ScienceAsked in: CDS · CDS-I 2026, GKMedium

Which one among the following pairs is not correctly matched ?

  1. A.Nitrogen : Three unpaired electrons
  2. B.Carbon : Tetravalent
  3. C.Chlorine : Two stable isotopic forms
  4. D.Helium : Diatomic gas
Show answer
Correct answer: D. Helium : Diatomic gas

Helium is a noble gas whose atoms exist singly, so it is a monatomic gas, not a diatomic one. Helium has a completely filled first shell (1s²), so its atoms have no tendency to share electrons or bond with each other.

Q95.General ScienceAsked in: NDA · NDA-I 2026, GATHard

With respect to electromagnetic waves, the human eye is sensitive to

  1. A.both electric and magnetic fields
  2. B.electric field only
  3. C.magnetic field only
  4. D.infrared part of the electromagnetic spectrum
Show answer
Correct answer: B. electric field only

Vision is caused by the electric field of light acting on the light-sensitive molecules of the retina. Light is an electromagnetic wave in which electric and magnetic fields oscillate at right angles to each other and to the direction of travel.

Q97.General ScienceAsked in: NDA · NDA-II 2026, GATMedium

Two astronauts X and Y float in deep space far from external forces. Initially, they are at rest relative to one another. X throws a tool towards Y. Consider the two astronauts and the tool as one system. Which one of the following statements is correct ?

  1. A.The centre of mass of the system moves towards Y.
  2. B.X moves and the centre of mass of the system follows him.
  3. C.The centre of mass follows the tool.
  4. D.The centre of mass remains fixed.
Show answer
Correct answer: D. The centre of mass remains fixed.

With no external force on the system, its centre of mass cannot start moving. The throw is an internal force: X pushes the tool forward and the tool pushes X backward with an equal and opposite force (Newton's third law).

Q98.General ScienceAsked in: CDS · CDS-I 2026, GKMedium

Consider the following statements regarding matter : 1. Elements cannot be broken down into simpler substances. 2. A compound has variable composition and can be broken down into elements. 3. The solution of sulphur in carbon disulphide is an example of a homogeneous mixture. Which of the statements given above is/are not correct ?

  1. A.2 only
  2. B.1 and 3
  3. C.3 only
  4. D.1 and 2
Show answer
Correct answer: A. 2 only

Statement 2 is the only incorrect one, because a compound always has a fixed composition, not a variable one. An element is the simplest form of matter and cannot be broken down into simpler substances by chemical reactions, so statement 1 is correct.

Q99.General ScienceAsked in: NDA · NDA-I 2026, GATEasy

It has been observed that a mirror always forms the image between the pole and the focus, irrespective of the location of the object. Which one of the following is correct in respect of the nature of the mirror?

  1. A.It is a plane mirror.
  2. B.It is a convex mirror.
  3. C.It is a concave mirror of small focal length.
  4. D.It is a concave mirror of large focal length.
Show answer
Correct answer: B. It is a convex mirror.

For any real object, a convex mirror forms a virtual, erect and smaller image behind the mirror, between the pole and the focus.

Q100.General ScienceAsked in: NDA · NDA-II 2026, GATHard

A heating filament and an ideal resistor of fixed value are connected in series with a DC voltage source. After some time, the filament has reached its operating point so that the current in the circuit is steady. Which one of the following is correct?

  1. A.The steady current is larger than the initial value.
  2. B.The steady voltage across the ideal resistor decreases as compared to its initial value.
  3. C.Overall resistance of the circuit decreases.
  4. D.Power dissipation through the filament increases as compared to its initial value.
Show answer
Correct answer: B. The steady voltage across the ideal resistor decreases as compared to its initial value.

A metal filament's resistance rises as it heats up, so the current falls and the resistor gets a smaller share of the voltage.