Pariksha SaathiGeneral Studies
General Science: Practice Questions with Answers
480 practice questions on General Science, with answers; most also have an explanation or a worked solution. Try each one before you open its answer.
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Q.1
Light travels at 3 x 10^8 m/s in vacuum and at 2 x 10^8 m/s in a certain type of glass. The refractive index of this glass is
- A 1.5
- B 0.67
- C 1.33
- D 2.0
Show answer
Correct answer: (A) 1.5
Refractive index = speed of light in vacuum / speed of light in the medium = (3 x 10^8) / (2 x 10^8) = 1.5.
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Q.2
A ball is dropped from a height. Neglecting air resistance, which statement is correct while it falls?
- A Both its potential energy and kinetic energy increase
- B Its potential energy increases and its kinetic energy decreases
- C Its potential energy decreases, its kinetic energy increases, and their sum stays constant
- D Its total mechanical energy decreases
Show answer
Correct answer: (C) Its potential energy decreases, its kinetic energy increases, and their sum stays constant
As the ball falls, its height decreases and its speed increases, so potential energy is converted into kinetic energy. With no air resistance, the total mechanical energy (PE + KE) remains constant.
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Q.3
'Dry ice', used for keeping ice cream and other foods frozen during transport, is solid
- A Carbon dioxide
- B Water
- C Nitrogen
- D Ammonia
Show answer
Correct answer: (A) Carbon dioxide
Dry ice is solid carbon dioxide. At about –78 °C it changes directly into gas (sublimes) without forming any liquid, which is why it is called 'dry'.
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Q.4
The ability of the eye lens to adjust its focal length so that both near and distant objects can be seen clearly is called
- A Persistence of vision
- B Dispersion
- C Power of accommodation
- D Presbyopia
Show answer
Correct answer: (C) Power of accommodation
The ciliary muscles change the curvature of the eye lens and thus adjust its focal length; this is the power of accommodation. Presbyopia is the weakening of this ability with age.
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Q.5
Ocean tides are caused mainly by the
- A Earth's magnetic field
- B gravitational pull of the Moon
- C strong winds blowing over the sea
- D rotation of the Earth alone
Show answer
Correct answer: (B) gravitational pull of the Moon
Tides are caused mainly by the Moon's gravitational pull on the Earth's oceans, with a smaller contribution from the Sun. This is one of the phenomena explained by the universal law of gravitation.
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Q.6
Which blood vessels carry blood away from the heart to the various organs of the body?
- A Veins
- B Capillaries
- C Lymph vessels
- D Arteries
Show answer
Correct answer: (D) Arteries
Arteries carry blood away from the heart under high pressure, so they have thick, elastic walls. Veins bring blood back to the heart, and capillaries link arteries with veins.
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Q.7
The 'father of genetics', who discovered the laws of inheritance by experimenting on garden pea plants, was
- A Gregor Mendel
- B Charles Darwin
- C Jean Baptiste Lamarck
- D T.H. Morgan
Show answer
Correct answer: (A) Gregor Mendel
Mendel worked on Pisum sativum and gave the laws of dominance, segregation and independent assortment. Darwin gave the theory of natural selection and Lamarck the theory of inheritance of acquired characters.
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Q.8
An electric generator (dynamo) converts
- A Electrical energy into mechanical energy
- B Mechanical energy into electrical energy
- C Chemical energy into electrical energy
- D Heat energy into electrical energy
Show answer
Correct answer: (B) Mechanical energy into electrical energy
A generator uses electromagnetic induction to convert mechanical energy into electrical energy. An electric motor does the reverse, and a cell converts chemical energy into electrical energy.
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Q.9
Stainless steel, which is hard and does not rust, is made by mixing iron with
- A Nickel and chromium
- B Copper and zinc
- C Lead and tin
- D Mercury and silver
Show answer
Correct answer: (A) Nickel and chromium
Stainless steel is an alloy of iron with nickel and chromium (along with a little carbon); these metals make it hard and resistant to rusting.
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Q.10
In a vacuum, a heavy iron ball and a light feather are dropped together from the same height. Which statement is correct?
- A The iron ball reaches the ground first
- B The feather reaches the ground first
- C Both reach the ground at the same time
- D The feather does not fall at all
Show answer
Correct answer: (C) Both reach the ground at the same time
In the absence of air resistance, all bodies fall with the same acceleration g, which does not depend on their mass. So both reach the ground together.
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Q.11
Silver articles turn black after some time when exposed to air. The black coating is
- A Silver oxide
- B Silver chloride
- C Silver sulphide
- D Silver nitrate
Show answer
Correct answer: (C) Silver sulphide
Silver reacts with sulphur compounds in the air to form a black coating of silver sulphide; this is a form of corrosion. Copper, by comparison, gets a green coating of basic copper carbonate.
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Q.12
The normal blood pressure (systolic/diastolic) of a healthy adult is about
- A 80/120 mm Hg
- B 160/110 mm Hg
- C 120/80 mm Hg
- D 60/40 mm Hg
Show answer
Correct answer: (C) 120/80 mm Hg
Normal systolic pressure (when the ventricles contract) is about 120 mm of mercury and diastolic pressure (when they relax) is about 80 mm. Systolic pressure is always the higher of the two, so 80/120 is not possible.
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Q.13
One nanometre (1 nm) is equal to
- A 10⁻⁶ m
- B 10⁻¹⁰ m
- C 10⁻¹² m
- D 10⁻⁹ m
Show answer
Correct answer: (D) 10⁻⁹ m
The prefix nano means 10⁻⁹, so 1 nm = 10⁻⁹ m. 10⁻⁶ m is a micrometre (micron), 10⁻¹⁰ m is an angstrom and 10⁻¹² m is a picometre.
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Q.14
Which of the following radiations has the highest penetrating power?
- A Alpha rays
- B Beta rays
- C Cathode rays
- D Gamma rays
Show answer
Correct answer: (D) Gamma rays
Gamma rays are electromagnetic waves with no charge or mass and can pass through several centimetres of lead. Alpha particles are stopped by a sheet of paper and beta particles by a few millimetres of aluminium.
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Q.15
The finger-like projections called villi on the inner wall of the small intestine mainly
- A Secrete bile
- B Increase the surface area for absorption of digested food
- C Produce hydrochloric acid
- D Store undigested food
Show answer
Correct answer: (B) Increase the surface area for absorption of digested food
Villi greatly increase the absorbing surface of the small intestine and are richly supplied with blood vessels, which carry the absorbed food to every cell of the body. Bile comes from the liver and hydrochloric acid from the stomach.
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Q.16
Unsaturated hydrocarbons, when burnt in air, generally give
- A a clean blue flame
- B no flame, only smoke
- C a yellow flame with lots of black smoke
- D a bright green flame
Show answer
Correct answer: (C) a yellow flame with lots of black smoke
Unsaturated hydrocarbons burn incompletely in air and give a yellow flame with lots of black smoke (soot), whereas saturated hydrocarbons generally give a clean blue flame.
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Q.17
Which of the following common name-chemical name pairs is correctly matched?
- A Marsh gas - Ethane
- B Dry ice - Solid sulphur dioxide
- C Vinegar - Formic acid
- D Laughing gas - Nitrous oxide
Show answer
Correct answer: (D) Laughing gas - Nitrous oxide
Laughing gas is nitrous oxide (N2O), used as an anaesthetic. Marsh gas is methane, dry ice is solid carbon dioxide and vinegar is dilute acetic acid; formic acid is found in ant stings.
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Q.18
What is the weight of a body of mass 10 kg on the Earth's surface? (Take g = 9.8 m/s²)
- A 98 N
- B 10 N
- C 9.8 N
- D 0.98 N
Show answer
Correct answer: (A) 98 N
Weight is the force with which the Earth attracts a body: W = mg = 10 kg × 9.8 m/s² = 98 N. Weight is measured in newton, while mass is measured in kilogram.
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Q.19
Which cell organelle is called the 'suicide bag' of the cell?
- A Ribosome
- B Mitochondrion
- C Lysosome
- D Plastid
Show answer
Correct answer: (C) Lysosome
Lysosomes contain digestive enzymes that break down worn-out organelles and, when the cell is damaged, burst and digest the whole cell. Mitochondria are the powerhouse of the cell and ribosomes make proteins.
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Q.20
The amount of heat energy required to change 1 kg of a solid into liquid at atmospheric pressure, at its melting point, is called
- A Specific heat capacity
- B Latent heat of vaporisation
- C Latent heat of fusion
- D Heat of combustion
Show answer
Correct answer: (C) Latent heat of fusion
This is the latent heat of fusion. Latent heat of vaporisation is the heat needed to change 1 kg of a liquid into gas at its boiling point, and specific heat capacity is the heat needed to raise the temperature of 1 kg of a substance by 1 K.
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Q.21
Which of the following is a pure substance?
- A Air
- B Brass
- C Milk
- D Sodium chloride
Show answer
Correct answer: (D) Sodium chloride
Sodium chloride is a compound with a fixed composition, so it is a pure substance. Air is a mixture of gases, brass is an alloy (a mixture of copper and zinc) and milk is a colloidal mixture.
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Q.22
The growth of a pollen tube towards the ovule is an example of
- A Phototropism
- B Geotropism
- C Chemotropism
- D Hydrotropism
Show answer
Correct answer: (C) Chemotropism
The pollen tube grows towards the ovule in response to chemicals, so this directional growth is chemotropism. Phototropism, geotropism and hydrotropism are responses to light, gravity and water respectively.
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Q.23
Which of the following oxides is amphoteric, that is, it reacts with both acids and bases to form salt and water?
- A Sodium oxide
- B Calcium oxide
- C Aluminium oxide
- D Sulphur dioxide
Show answer
Correct answer: (C) Aluminium oxide
Aluminium oxide (like zinc oxide) shows both acidic and basic behaviour: Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O and Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O. Sodium oxide and calcium oxide are basic, and sulphur dioxide is acidic.
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Q.24
When solutions of sodium sulphate and barium chloride are mixed, a white precipitate is formed. The precipitate is
- A Sodium chloride
- B Barium sulphate
- C Barium chloride
- D Sodium sulphate
Show answer
Correct answer: (B) Barium sulphate
Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl. The ions are exchanged (double displacement), and insoluble barium sulphate separates as a white precipitate while sodium chloride stays dissolved.
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Q.25
A ship sends an ultrasonic pulse towards the sea bed and receives its echo after 4 s. If the speed of sound in sea water is 1500 m/s, the depth of the sea is
- A 1500 m
- B 6000 m
- C 3000 m
- D 375 m
Show answer
Correct answer: (C) 3000 m
The pulse goes down and comes back, covering 2d = speed x time = 1500 x 4 = 6000 m, so the depth d = 3000 m. SONAR measures sea depth in this way.
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Q.26
A sharp knife cuts vegetables more easily than a blunt knife because
- A the sharp edge has a smaller area, so the same force produces greater pressure
- B the sharp knife is heavier
- C the sharp edge has a larger area, so the pressure is less
- D the blunt knife has more friction with the hand
Show answer
Correct answer: (A) the sharp edge has a smaller area, so the same force produces greater pressure
Pressure = force ÷ area. The thin edge of a sharp knife has a very small area, so even a small force produces a large pressure that cuts easily.
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Q.27
Water has its maximum density at
- A 0 degrees Celsius
- B 4 degrees Celsius
- C 100 degrees Celsius
- D -4 degrees Celsius
Show answer
Correct answer: (B) 4 degrees Celsius
Because of anomalous expansion, water is densest at 4 degrees C. This is why ice floats and lakes freeze from the top, allowing aquatic life to survive below.
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Q.28
White silver chloride turns grey when kept in sunlight. This is because
- A It combines with oxygen to form silver oxide
- B It absorbs moisture from the air
- C It decomposes into silver and chlorine in the presence of light
- D It reacts with nitrogen in the air
Show answer
Correct answer: (C) It decomposes into silver and chlorine in the presence of light
Sunlight decomposes silver chloride: 2AgCl → 2Ag + Cl₂. The grey colour is due to the silver formed; this decomposition by light is used in black and white photography.
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Q.29
Which of the following animals has a three-chambered heart?
- A Frog
- B Rohu fish
- C Pigeon
- D Rabbit
Show answer
Correct answer: (A) Frog
Amphibians such as the frog have a three-chambered heart (two atria and one ventricle). Fishes have a two-chambered heart, while birds (pigeon) and mammals (rabbit) have four chambers.
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Q.30
Bacteria and blue-green algae (cyanobacteria) are placed in which kingdom?
- A Monera
- B Protista
- C Fungi
- D Plantae
Show answer
Correct answer: (A) Monera
Monera includes prokaryotic organisms, which lack a well-defined nucleus and membrane-bound organelles, such as bacteria and blue-green algae. Protista includes unicellular eukaryotes such as Amoeba and Paramecium.
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Q.31
In the presence of sunlight, methane reacts with chlorine to form chloromethane (CH₃Cl) and hydrogen chloride. This is an example of
- A a substitution reaction
- B an addition reaction
- C a neutralisation reaction
- D a polymerisation reaction
Show answer
Correct answer: (A) a substitution reaction
CH₄ + Cl₂ → CH₃Cl + HCl (in sunlight). A hydrogen atom of methane is replaced by a chlorine atom, so it is a substitution reaction; saturated hydrocarbons do not undergo addition reactions.
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Q.32
A gun of mass 4 kg fires a bullet of mass 20 g with a velocity of 400 m/s. The recoil velocity of the gun is
- A 1 m/s
- B 2 m/s
- C 4 m/s
- D 8 m/s
Show answer
Correct answer: (B) 2 m/s
Total momentum before firing is zero, so m₁v₁ = m₂v₂: 0.02 kg × 400 m/s = 4 kg × v, giving v = 8/4 = 2 m/s, in the direction opposite to the bullet.
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Q.33
Astronauts on the Moon cannot hear each other directly even when standing close together because
- A the Moon's gravity is too weak
- B sound travels too fast on the Moon
- C the temperature on the Moon is too low
- D there is no air on the Moon to carry sound
Show answer
Correct answer: (D) there is no air on the Moon to carry sound
Sound is a mechanical wave and needs a material medium to travel. The Moon has practically no atmosphere, so sound cannot pass from one astronaut to another; they talk by radio, which, being an electromagnetic wave, can travel through vacuum.
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Q.34
Which of the following vitamins is fat-soluble?
- A Vitamin C
- B Vitamin B1
- C Vitamin E
- D Vitamin B12
Show answer
Correct answer: (C) Vitamin E
Vitamins A, D, E and K dissolve in fat and can be stored in the body. The B-group vitamins and vitamin C are water-soluble.
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Q.35
Electrical appliances in a house are connected in parallel rather than in series because
- A this makes the total resistance of the circuit maximum
- B this makes the same current flow through every appliance
- C each appliance then gets the full supply voltage and can be switched on or off independently
- D this needs less wire than a series connection
Show answer
Correct answer: (C) each appliance then gets the full supply voltage and can be switched on or off independently
In parallel, every appliance is connected directly across the supply, so each gets the full voltage, draws the current it needs, and can be switched off without affecting the others. A parallel connection actually lowers the total resistance.
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Q.36
The cell was first observed and named by
- A Robert Brown
- B Antonie van Leeuwenhoek
- C Matthias Schleiden
- D Robert Hooke
Show answer
Correct answer: (D) Robert Hooke
Robert Hooke saw the honeycomb-like compartments in a thin slice of cork in 1665 and called them cells. Leeuwenhoek first saw living cells, Robert Brown discovered the nucleus, and Schleiden and Schwann gave the cell theory.
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Q.37
In a food chain, 10,000 J of energy is available at the producer level. According to the 10 per cent law, how much energy will be available to the secondary consumers?
- A 1 J
- B 10 J
- C 100 J
- D 1000 J
Show answer
Correct answer: (C) 100 J
Only about 10% of the energy passes from one trophic level to the next. Producers 10,000 J → primary consumers (herbivores) 1000 J → secondary consumers 100 J.
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Q.38
Deficiency of growth hormone, secreted by the pituitary gland, in childhood leads to
- A Goitre
- B Dwarfism
- C Diabetes
- D Night blindness
Show answer
Correct answer: (B) Dwarfism
Growth hormone from the pituitary regulates growth and development of the body; its deficiency in childhood causes dwarfism. Goitre is linked to iodine deficiency, diabetes to insulin and night blindness to vitamin A deficiency.
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Q.39
The theory of evolution by natural selection was proposed by
- A Charles Darwin
- B Gregor Mendel
- C Jean-Baptiste Lamarck
- D Hugo de Vries
Show answer
Correct answer: (A) Charles Darwin
Charles Darwin explained in 'On the Origin of Species' (1859) that organisms better suited to their environment survive and reproduce more, so their traits spread. Lamarck proposed the inheritance of acquired characters, Mendel worked out the laws of inheritance and de Vries proposed the idea of mutations.
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Q.40
A car of mass 1500 kg moving at 20 m/s is stopped in 10 s by applying the brakes. The average braking force is
- A 300 N
- B 3000 N
- C 30,000 N
- D 750 N
Show answer
Correct answer: (B) 3000 N
Change in momentum = 1500 × (0 − 20) = −30,000 kg m/s. Force = change in momentum ÷ time = 30,000 ÷ 10 = 3000 N, acting opposite to the motion.
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Q.41
An element X has the electronic configuration 2, 8, 2. Which statement about X is correct?
- A It is a non-metal that forms X²⁻ ions
- B It is a metal that forms X²⁺ ions
- C It is a noble gas
- D It is a metal that forms X⁻ ions
Show answer
Correct answer: (B) It is a metal that forms X²⁺ ions
With 2 electrons in its outermost shell, X (magnesium, atomic number 12) easily loses them to form a stable X²⁺ ion, which is typical of metals. Non-metals gain electrons to form negative ions.
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Q.42
Which statement about transport in plants is correct?
- A Xylem carries food from the leaves to the roots
- B Sucrose is moved into the phloem using energy from ATP
- C Phloem carries only water, and only upwards
- D Xylem is made up of sieve tubes and companion cells
Show answer
Correct answer: (B) Sucrose is moved into the phloem using energy from ATP
Sucrose is loaded into the phloem using energy from ATP; this raises the osmotic pressure, water enters, and the pressure pushes the food along, upwards or downwards as needed. Xylem (tracheids and vessels) carries water and minerals; sieve tubes and companion cells belong to the phloem.
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Q.43
The SI unit of pressure is
- A Newton
- B Pascal
- C Joule
- D Watt
Show answer
Correct answer: (B) Pascal
Pressure is force per unit area, so its SI unit is newton per square metre, named the pascal (Pa). Newton is the unit of force, joule of energy and watt of power.
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Q.44
When phenolphthalein indicator is added to a basic (alkaline) solution, the solution turns
- A Colourless
- B Pink
- C Red
- D Yellow
Show answer
Correct answer: (B) Pink
Phenolphthalein is colourless in acid and pink in base. Litmus is red in acid and blue in base, while methyl orange is red in acid and yellow in base.
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Q.45
A body starts from rest and moves with a uniform acceleration of 4 m/s². The distance covered by it in the first 5 s is
- A 50 m
- B 20 m
- C 100 m
- D 25 m
Show answer
Correct answer: (A) 50 m
s = ut + ½at² = 0 + ½ × 4 × 5² = 50 m. The answer 100 m comes from forgetting the ½.
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Q.46
Dengue and chikungunya are spread by the bite of which mosquito?
- A Anopheles
- B Aedes aegypti
- C Culex
- D Sandfly
Show answer
Correct answer: (B) Aedes aegypti
Aedes aegypti, a day-biting mosquito that breeds in clean stagnant water, spreads dengue, chikungunya, zika and yellow fever. Anopheles spreads malaria, Culex spreads filaria and Japanese encephalitis, and the sandfly spreads kala-azar.
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Q.47
Which two cell organelles have their own DNA and ribosomes?
- A Golgi apparatus and lysosomes
- B Endoplasmic reticulum and Golgi apparatus
- C Mitochondria and plastids
- D Vacuoles and lysosomes
Show answer
Correct answer: (C) Mitochondria and plastids
Mitochondria and plastids have their own DNA and ribosomes, so they can make some of their own proteins. The Golgi apparatus, endoplasmic reticulum, vacuoles and lysosomes have no DNA of their own.
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Q.48
The husk of a coconut is made of which tissue?
- A Parenchyma
- B Collenchyma
- C Sclerenchyma
- D Chlorenchyma
Show answer
Correct answer: (C) Sclerenchyma
Sclerenchyma cells are dead, long and narrow, with walls thickened by lignin, which makes the tissue hard and stiff; the coconut husk is made of it. Parenchyma, collenchyma and chlorenchyma are made of living cells.
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Q.49
Which of the following metals is the most reactive?
- A Sodium
- B Magnesium
- C Calcium
- D Potassium
Show answer
Correct answer: (D) Potassium
In the reactivity series K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au, potassium stands at the top and reacts violently even with cold water.
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Q.50
What is the IUPAC name of acetone, CH₃COCH₃?
- A Propanal
- B Propanone
- C Propanol
- D Propanoic acid
Show answer
Correct answer: (B) Propanone
CH₃COCH₃ has three carbon atoms (prop-) and a ketone group, >C=O, on the middle carbon, so its name ends in '-one': propanone. Propanal is an aldehyde, propanol an alcohol and propanoic acid a carboxylic acid.
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How these questions were made
Authored by an AI assistant (Claude) from its own general knowledge of stable, well-established facts (no live lookup) - not reviewed by a subject-matter expert; verify against an official source before relying on any fact.