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General Science Previous Year Questions (PYQ) with Answers – Page 24

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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
Q461.General ScienceAsked in: NDA · NDA-I 2023, GATMedium

In an electric circuit, a wire of resistance 10 Ω is used. If this wire is stretched to a length double of its original value, the current in the circuit would become :

  1. A.half of its original value.
  2. B.double of its original value.
  3. C.one-fourth of its original value.
  4. D.four times of its original value.
Show answer
Correct answer: C. one-fourth of its original value.

Stretching the wire to twice its length makes its resistance four times larger, so at the same voltage the current falls to a quarter.

Q462.General ScienceAsked in: NDA · NDA-I 2023, GATEasy

A mass is attached to a spring that hangs vertically. The extension produced in the spring is 6 cm on Earth. The acceleration due to gravity on the surface of the Moon is one-sixth of its value on the surface of the Earth. The extension of the spring on the Moon would be :

  1. A.6 cm
  2. B.1 cm
  3. C.0 cm
  4. D.36 cm
Show answer
Correct answer: B. 1 cm

The stretch of a spring is proportional to the force on it, and the weight of the mass on the Moon is one-sixth of its weight on Earth.

Q463.General ScienceAsked in: NDA · NDA-I 2023, GATHard

One block of 2.0 kg mass is placed on top of another block of 3.0 kg mass. The coefficient of static friction between the two blocks is 0.2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s², the maximum value of the frictional force is :

  1. A.50 N
  2. B.30 N
  3. C.4 N
  4. D.10 N
Show answer
Correct answer: C. 4 N

The friction between the blocks is the only force that drags the top block along, and its largest possible value is μ times the normal force from the top block.

Q465.General ScienceAsked in: NDA · NDA-I 2023, GATHard

Sand falls vertically on a conveyor belt at a rate of 0.1 kg/s. In order to keep the belt moving at a uniform speed of 2 m/s, the force required to be applied on the belt is :

  1. A.0 N
  2. B.0.2 N
  3. C.1.0 N
  4. D.2.0 N
Show answer
Correct answer: B. 0.2 N

The force needed equals the rate at which the belt must give horizontal momentum to the falling sand: F = v × (dm/dt) = 2 × 0.1 = 0.2 N. Newton's second law, in its general form, says force equals the rate of change of momentum.

Q466.General ScienceAsked in: NDA · NDA-II 2023, GATMedium

Which among the following statements with respect to carbon is/are correct?

1. Carbon forms the basis for all living organisms and many things we use

2. Carbon shows tetra-valency and the property of catenation

3. Carbon forms covalent bonds with itself and other elements

4. Carbon forms compounds containing triple and tetra bonds between carbon atoms

Select the correct answer using the code given below :

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

Statements 1, 2 and 3 are true, but carbon never forms a quadruple, or tetra, bond between two carbon atoms.

Q467.General ScienceAsked in: NDA · NDA-I 2023, GATMedium

Airbags work on the principle of a chemical reaction triggered by the impact producing a gaseous product that causes a sudden volume change. Which one among the following chemical conversions is responsible for this ?

  1. A.Sodium azide into nitrogen gas
  2. B.Solid carbon dioxide into gaseous carbon dioxide
  3. C.Carbon dioxide into carbon monoxide
  4. D.Sudden conversion of gaseous carbon dioxide into carbon monoxide
Show answer
Correct answer: A. Sodium azide into nitrogen gas

In a crash a sensor fires an igniter, and sodium azide breaks down almost instantly into sodium and a large volume of nitrogen gas that fills the bag.

Q468.General ScienceAsked in: NDA · NDA-II 2023, GATMedium

Kerosene and petrol mixture can be best separated by

  1. A.Sublimation
  2. B.Separating funnel
  3. C.Fractional distillation
  4. D.Compressing and cooling
Show answer
Correct answer: C. Fractional distillation

Kerosene and petrol mix completely with each other, and their boiling points are close, so they are separated by fractional distillation.

Q469.General ScienceAsked in: NDA · NDA-I 2023, GATEasy

Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour?

  1. A.Oxygen
  2. B.Nitrogen
  3. C.Water
  4. D.Hydrogen
Show answer
Correct answer: C. Water

The blue colour comes from water of crystallisation: blue vitriol is CuSO4·5H2O, and heating drives off these five water molecules to leave white anhydrous copper sulphate.

Q473.General ScienceAsked in: NDA · NDA-II 2023, GATMedium

What will happen if a collection of positive and negative charges are passed at a high speed through a magnetic field which is perpendicular to the direction of motion of the charges ? (Assume that both kind of charges are NOT going to recombine)

  1. A.Both kind of charges will stop moving
  2. B.Positive charges and negative charges will separate out
  3. C.Positive charges will stop but negative charges will continue moving uninterrupted
  4. D.Both kind of charges will keep moving uninterrupted
Show answer
Correct answer: B. Positive charges and negative charges will separate out

A magnetic field pushes a moving charge sideways, and the push on a negative charge is opposite to that on a positive one, so the two kinds bend away from each other.

Q474.General ScienceAsked in: NDA · NDA-I 2023, GATEasy

Which among the following is the popular method for manufacture of ammonia ?

  1. A.Ostwald's process
  2. B.Haber-Bosch process
  3. C.Electric furnace process
  4. D.Electrolysis process
Show answer
Correct answer: B. Haber-Bosch process

Almost all the world's ammonia is made by combining nitrogen and hydrogen directly in this process. In the Haber-Bosch process, nitrogen from the air and hydrogen, usually obtained from natural gas, are made to react in the ratio 1 to 3.

Q475.General ScienceAsked in: NDA · NDA-II 2023, GATEasy

An iron nail sinks in water whereas an iron ship floats. Which of the following statements is correct in this regard?

1. Average density of ship is greater than that of the water

2. Average density of iron nail is greater than that of the water

3. Average density of the ship is less than that of the water

4. Average density of the ship is equal to that of the water

Select the correct answer using the code given below:

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

An object floats when its average density is less than that of the liquid and sinks when it is greater.

Q476.General ScienceAsked in: NDA · NDA-I 2023, GATEasy

Which one of the following is the correct arrangement of metals in the decreasing order of their reactivity?

  1. A.Iron, Sodium, Silver, Copper
  2. B.Silver, Copper, Iron, Sodium
  3. C.Sodium, Copper, Silver, Iron
  4. D.Sodium, Iron, Copper, Silver
Show answer
Correct answer: D. Sodium, Iron, Copper, Silver

This matches the reactivity series, which lists metals from the most to the least reactive. Sodium is near the top: it reacts violently with cold water and is stored under kerosene.

Q477.General ScienceAsked in: NDA · NDA-I 2023, GATMedium

What is the specific purpose of using potassium hydroxide during the saponification process?

  1. A.To obtain soaps which are hard on the skin
  2. B.To obtain soaps which are soft on the skin
  3. C.To obtain natural fragrance
  4. D.To make the saponification very economical
Show answer
Correct answer: B. To obtain soaps which are soft on the skin

Potassium hydroxide gives potassium soaps, which are softer and milder than sodium soaps. Saponification is the reaction in which an oil or fat is heated with an alkali to give soap, the sodium or potassium salt of a long-chain fatty acid, and glycerol.

Q478.General ScienceAsked in: NDA · NDA-I 2023, GATMedium

Which one of the following statements about bryophytes is not correct ?

  1. A.The plant body is a gametophyte.
  2. B.They are also called the amphibians of plant kingdom.
  3. C.The plant body is attached to the substratum by rhizoids.
  4. D.Specialized water-conducting tissues are present.
Show answer
Correct answer: D. Specialized water-conducting tissues are present.

This statement is wrong because bryophytes, the mosses and liverworts, have no true vascular tissue: they lack xylem to carry water and phloem to carry food.

Q480.General ScienceAsked in: NDA · NDA-I 2023, GATMedium

During a laboratory experiment, a student immerses epidermal leaf peel in a hypertonic solution. After some time, the student examined the cells under a microscope and observed that:

  1. A.the cells swelled.
  2. B.the cells were plasmolysed.
  3. C.the cells built up turgor pressure.
  4. D.the cells size was unaffected.
Show answer
Correct answer: B. the cells were plasmolysed.

A hypertonic solution has a higher solute concentration than the cell sap, so water leaves the cells by osmosis and the protoplast shrinks away from the cell wall.