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.201
In the hydrogenation of vegetable oils to make vanaspati ghee, the catalyst used is
- A Iron
- B Platinum
- C Nickel
- D Copper
Show answer
Correct answer: (C) Nickel
Finely divided nickel catalyses the addition of hydrogen to unsaturated oils, converting them into solid fats. Iron is the catalyst in the Haber process and vanadium pentoxide in the contact process.
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Q.202
During sudden vigorous exercise, when the oxygen supply to our muscle cells falls short, pyruvate in these cells is broken down anaerobically into
- A Lactic acid
- B Ethanol
- C Urea
- D Carbon dioxide
Show answer
Correct answer: (A) Lactic acid
When oxygen falls short during heavy exercise, muscle cells break pyruvate down without oxygen into lactic acid, releasing a small amount of energy; NCERT links the build-up of this lactic acid to muscle cramps. Ethanol and carbon dioxide are the products of anaerobic respiration in yeast, and anaerobic respiration in our muscles gives no carbon dioxide. Urea is a nitrogenous waste made in the liver.
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Q.203
In the scientific name Homo sapiens, the word 'Homo' denotes the
- A Species
- B Family
- C Order
- D Genus
Show answer
Correct answer: (D) Genus
In binomial nomenclature the first word is the genus and the second the species, so Homo is the genus and sapiens the species. The genus name begins with a capital letter and the species name with a small letter.
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Q.204
Which plant hormone promotes cell division and is found in high concentration in fruits and seeds?
- A Abscisic acid
- B Ethylene
- C Auxin
- D Cytokinin
Show answer
Correct answer: (D) Cytokinin
Cytokinins promote cell division, so they are present in large amounts in regions of rapid cell division such as fruits and seeds. Abscisic acid inhibits growth and ethylene helps fruits ripen.
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Q.205
Arrange water, sugar and oxygen in increasing order of the forces of attraction between their particles.
- A Sugar < water < oxygen
- B Water < oxygen < sugar
- C Oxygen < water < sugar
- D Oxygen < sugar < water
Show answer
Correct answer: (C) Oxygen < water < sugar
Oxygen is a gas, so its particles attract one another the least; water is a liquid; sugar is a solid with the strongest forces of attraction between its particles. Hence oxygen < water < sugar.
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Q.206
Which of the following is true of a compound but NOT of a mixture?
- A Its components can be separated by physical methods
- B Its constituents are present in a fixed ratio by mass
- C It shows the properties of its constituents
- D It can have a variable composition
Show answer
Correct answer: (B) Its constituents are present in a fixed ratio by mass
In a compound the elements combine in a fixed proportion by mass, and the compound has properties different from those of its constituents. A mixture has a variable composition, keeps the properties of its components and can be separated by physical methods.
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Q.207
The core of an electromagnet is made of soft iron because soft iron
- A retains its magnetism permanently
- B is a non-magnetic material
- C is a poor conductor of electricity
- D becomes strongly magnetised when current flows and loses most of its magnetism when the current is switched off
Show answer
Correct answer: (D) becomes strongly magnetised when current flows and loses most of its magnetism when the current is switched off
An electromagnet should be a magnet only while the current flows; soft iron is strongly magnetised by the current and loses almost all its magnetism when the current stops. Steel, which retains magnetism, is used for permanent magnets.
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Q.208
The slope of a velocity-time graph gives the
- A displacement
- B speed
- C acceleration
- D distance
Show answer
Correct answer: (C) acceleration
Slope of a v-t graph = change in velocity ÷ time taken, which is acceleration. Speed is given by the slope of a distance-time graph.
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Q.209
Two 4 Ω resistors are connected in parallel, and this combination is connected in series with a 3 Ω resistor. The total resistance is
- A 5 Ω
- B 11 Ω
- C 7 Ω
- D 1.2 Ω
Show answer
Correct answer: (A) 5 Ω
For the two 4 Ω resistors in parallel, 1/R = 1/4 + 1/4, so R = 2 Ω. Adding the 3 Ω resistor in series gives 2 + 3 = 5 Ω.
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Q.210
Horsepower (hp) is a unit of
- A power
- B force
- C energy
- D momentum
Show answer
Correct answer: (A) power
Horsepower is a unit of power, the rate of doing work; 1 hp is about 746 W. Force is measured in newton, energy in joule and momentum in kg m/s.
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Q.211
Urea, a widely used nitrogenous fertiliser, has the chemical formula
- A NH₄NO₃
- B (NH₄)₂SO₄
- C NH₄Cl
- D CO(NH₂)₂
Show answer
Correct answer: (D) CO(NH₂)₂
Urea is CO(NH₂)₂ (also written NH₂CONH₂) and contains about 46% nitrogen. NH₄NO₃ is ammonium nitrate, (NH₄)₂SO₄ is ammonium sulphate and NH₄Cl is ammonium chloride.
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Q.212
A temperature of 25 °C on the Kelvin scale is approximately
- A 273 K
- B 298 K
- C 25 K
- D 323 K
Show answer
Correct answer: (B) 298 K
Temperature in kelvin = temperature in °C + 273, so 25 °C = 25 + 273 = 298 K. 273 K corresponds to 0 °C and 323 K to 50 °C.
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Q.213
The SI base unit of temperature is the
- A degree Celsius
- B degree Fahrenheit
- C joule
- D kelvin
Show answer
Correct answer: (D) kelvin
Thermodynamic temperature is one of the seven SI base quantities and its unit is the kelvin (K). Degree Celsius and degree Fahrenheit are other temperature scales, and the joule is the unit of energy, including heat.
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Q.214
In a leaf cell, photosynthesis takes place in the
- A Chloroplasts
- B Mitochondria
- C Nucleus
- D Ribosomes
Show answer
Correct answer: (A) Chloroplasts
Chloroplasts contain chlorophyll, the green pigment that absorbs the light energy needed for photosynthesis. Mitochondria are the sites of respiration, the nucleus controls the activities of the cell and ribosomes make proteins.
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Q.215
A stone weighs 10 N in air and 6 N when fully immersed in water. The buoyant force acting on it in water is
- A 16 N
- B 6 N
- C 4 N
- D 10 N
Show answer
Correct answer: (C) 4 N
Buoyant force = apparent loss of weight = 10 N − 6 N = 4 N. By Archimedes' principle, this equals the weight of the water displaced by the stone.
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Q.216
Vulcanisation of natural rubber is carried out by heating it with
- A Carbon
- B Phosphorus
- C Chlorine
- D Sulphur
Show answer
Correct answer: (D) Sulphur
Charles Goodyear found that heating rubber with sulphur forms cross-links between the polymer chains, making it hard, elastic and less sticky. Vulcanised rubber is used in tyres.
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Q.217
The law of conservation of mass, which states that mass can neither be created nor destroyed in a chemical reaction, was established by
- A John Dalton
- B Joseph Proust
- C Antoine Lavoisier
- D Amedeo Avogadro
Show answer
Correct answer: (C) Antoine Lavoisier
Antoine L. Lavoisier established the law of conservation of mass. Joseph Proust gave the law of constant proportions, and Dalton based his atomic theory on these laws.
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Q.218
The number of particles (atoms, molecules or ions) present in one mole of a substance is
- A 6.022 x 10^22
- B 3.011 x 10^23
- C 6.022 x 10^23
- D 6.022 x 10^24
Show answer
Correct answer: (C) 6.022 x 10^23
One mole of any substance contains 6.022 x 10^23 particles; this fixed number is the Avogadro constant (Avogadro number).
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Q.219
Kala-azar is caused by the protozoan Leishmania. It is spread by the bite of the
- A Sandfly
- B Housefly
- C Tsetse fly
- D Female Anopheles mosquito
Show answer
Correct answer: (A) Sandfly
Kala-azar is spread by the bite of infected sandflies. The tsetse fly spreads sleeping sickness and the female Anopheles mosquito spreads malaria.
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Q.220
Fog is a colloid. Its dispersed phase and dispersion medium are respectively
- A Gas and liquid
- B Liquid and gas
- C Solid and gas
- D Liquid and liquid
Show answer
Correct answer: (B) Liquid and gas
In fog, tiny droplets of water (liquid) are dispersed in air (gas); such a colloid is called an aerosol. Gas in liquid is a foam (shaving cream), solid in gas is an aerosol such as smoke, and liquid in liquid is an emulsion (milk).
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Q.221
In a food chain, herbivores such as deer and rabbits occupy which trophic level?
- A First
- B Second
- C Third
- D Fourth
Show answer
Correct answer: (B) Second
Producers (green plants) form the first trophic level. Herbivores, which eat plants, are primary consumers at the second level, and carnivores that eat herbivores are at the third level.
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Q.222
Anodising is a process in which a thick protective oxide layer is formed on the surface of a metal to make it resistant to corrosion. It is commonly done on articles made of
- A Aluminium
- B Iron
- C Copper
- D Silver
Show answer
Correct answer: (A) Aluminium
In anodising, a clean aluminium article is made the anode and electrolysed with dilute sulphuric acid; the oxygen released thickens its natural oxide layer, which protects the metal and can be dyed. Iron is usually protected by painting or galvanising.
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Q.223
Which mirror is used as a rear-view mirror in vehicles, and why?
- A Concave mirror, because it gives a magnified image
- B Plane mirror, because it forms a real image
- C Concave mirror, because it gives a wider field of view
- D Convex mirror, because it gives an erect image and a wider field of view
Show answer
Correct answer: (D) Convex mirror, because it gives an erect image and a wider field of view
A convex mirror always forms an erect, diminished image and, being curved outwards, shows a much wider area behind the vehicle. A concave mirror does not give a wide field of view, and a plane mirror forms a virtual, not real, image.
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Q.224
The main nitrogenous waste excreted by human kidneys in urine is
- A Ammonia
- B Uric acid
- C Urea
- D Amino acids
Show answer
Correct answer: (C) Urea
In humans excess nitrogen is converted into urea in the liver, and the kidneys remove it in urine. Ammonia is the main nitrogenous waste of many aquatic animals such as bony fishes and uric acid that of birds, while amino acids are reabsorbed, not excreted.
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Q.225
An element X has a valency of 4. The formula of its oxide will be
- A X₂O
- B XO₂
- C X₄O
- D XO₄
Show answer
Correct answer: (B) XO₂
Oxygen has a valency of 2. Crossing over the valencies of X (4) and O (2) gives X₂O₄, which is written in its simplest ratio as XO₂, as in carbon dioxide (CO₂) and silicon dioxide (SiO₂).
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Q.226
Bleeding gums and slow healing of wounds are symptoms of scurvy, which is caused by the deficiency of
- A Vitamin A
- B Vitamin D
- C Vitamin B12
- D Vitamin C
Show answer
Correct answer: (D) Vitamin C
Scurvy results from a lack of vitamin C, which is found in citrus fruits such as orange and lemon and in amla. Vitamin D deficiency causes rickets.
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Q.227
Which of the following is a postulate of Bohr's model of the atom?
- A Electrons are embedded in a sphere of positive charge
- B Electrons revolve in any orbit and continuously radiate energy
- C Electrons revolve only in certain discrete orbits and do not radiate energy while in them
- D The nucleus contains both protons and electrons
Show answer
Correct answer: (C) Electrons revolve only in certain discrete orbits and do not radiate energy while in them
Bohr proposed that electrons move only in certain special (discrete) orbits, called energy levels or shells, without radiating energy. Electrons embedded in a sphere of positive charge is Thomson's model.
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Q.228
Permanent hardness of water is due to the presence of dissolved
- A Chlorides and sulphates of calcium and magnesium
- B Bicarbonates of calcium and magnesium
- C Carbon dioxide
- D Sodium chloride
Show answer
Correct answer: (A) Chlorides and sulphates of calcium and magnesium
Permanent hardness, caused by chlorides and sulphates of calcium and magnesium, cannot be removed by boiling and needs washing soda or ion exchange. Temporary hardness is due to bicarbonates and is removed by boiling.
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Q.229
The forelimbs of a frog, a lizard, a bird and a human have the same basic bone structure but are used for different functions. Such organs are called
- A Analogous organs
- B Vestigial organs
- C Homologous organs
- D Accessory organs
Show answer
Correct answer: (C) Homologous organs
Homologous organs have the same basic structure and origin but may perform different functions, which shows that these animals share a common ancestor. Analogous organs, like the wings of a bird and a butterfly, do the same job but differ in structure and origin.
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Q.230
The loss of water in the form of vapour from the aerial parts of a plant, mainly through the stomata, is called
- A Translocation
- B Guttation
- C Transpiration
- D Respiration
Show answer
Correct answer: (C) Transpiration
Transpiration is the evaporation of water from the leaves and other aerial parts, mostly through the stomata. Guttation is the loss of liquid water drops from leaf edges, and translocation is the transport of food within the plant.
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Q.231
The value of the universal gravitational constant G is
- A 9.8 N m²/kg²
- B 6.67 × 10⁻¹¹ N m²/kg²
- C 6.67 × 10¹¹ N m²/kg²
- D 6.67 × 10⁻⁹ N m²/kg²
Show answer
Correct answer: (B) 6.67 × 10⁻¹¹ N m²/kg²
G = 6.67 × 10⁻¹¹ N m²/kg² and is the same everywhere in the universe. 9.8 m/s² is the value of g, the acceleration due to gravity near the Earth's surface.
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Q.232
The pitch of a sound depends mainly on its
- A Amplitude
- B Speed in the medium
- C Frequency
- D Intensity
Show answer
Correct answer: (C) Frequency
Pitch is how high or shrill a sound is, and it is determined by frequency: the higher the frequency, the higher the pitch. Amplitude and intensity decide loudness, not pitch.
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Q.233
An ionic (electrovalent) bond is formed by the
- A Sharing of electron pairs between two atoms
- B Sharing of protons between two atoms
- C Weak attraction between neutral molecules
- D Transfer of electrons from one atom to another
Show answer
Correct answer: (D) Transfer of electrons from one atom to another
In NaCl, sodium gives its electron to chlorine, forming Na+ and Cl- ions held together by electrostatic attraction. Sharing of electron pairs gives a covalent bond, as in H2O or CH4.
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Q.234
Sound waves travelling through air are
- A Transverse waves
- B Longitudinal waves
- C Electromagnetic waves
- D Both transverse and electromagnetic waves
Show answer
Correct answer: (B) Longitudinal waves
In air, sound travels as a series of compressions and rarefactions, with the particles vibrating parallel to the direction of travel, so it is a longitudinal wave. Light is an electromagnetic (transverse) wave; sound is not.
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Q.235
Which of the following is NOT a noble gas?
- A Helium
- B Neon
- C Nitrogen
- D Argon
Show answer
Correct answer: (C) Nitrogen
The noble (inert) gases of group 18 are helium, neon, argon, krypton, xenon and radon, all with completely filled outer shells. Nitrogen is a group 15 element that exists as the diatomic molecule N2.
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Q.236
The largest part of the human brain, which is the main thinking part, is the
- A Medulla
- B Cerebrum
- C Cerebellum
- D Pons
Show answer
Correct answer: (B) Cerebrum
The cerebrum, part of the fore-brain, is the largest part of the brain; it handles thinking, memory and reasoning and has areas that receive sensory information. The medulla and pons are parts of the hind-brain.
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Q.237
A plant shoot bends towards light coming from one side. Which hormone causes this by moving to the shaded side and making the cells there grow longer?
- A Auxin
- B Abscisic acid
- C Ethylene
- D Cytokinin
Show answer
Correct answer: (A) Auxin
Auxin is made at the shoot tip. When light falls from one side, auxin diffuses to the shaded side and makes those cells elongate more, so the shoot bends towards the light (phototropism).
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Q.238
In human females, fertilisation of the egg by a sperm normally takes place in the
- A Uterus
- B Oviduct (fallopian tube)
- C Ovary
- D Vagina
Show answer
Correct answer: (B) Oviduct (fallopian tube)
The egg released from the ovary is carried into the thin oviduct (fallopian tube), where it meets a sperm and is fertilised. The fertilised egg (zygote) then moves to the uterus and gets implanted in its lining.
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Q.239
A person who can see nearby objects clearly but not distant ones suffers from myopia. It is corrected by using a
- A Convex lens
- B Concave lens
- C Cylindrical lens
- D Plano-convex lens
Show answer
Correct answer: (B) Concave lens
In myopia (short-sightedness) the image forms in front of the retina, so a diverging concave lens is used. Hypermetropia (long-sightedness) is corrected with a convex lens and astigmatism with a cylindrical lens.
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Q.240
In a flower, pollen grains are produced in the
- A Stigma
- B Ovary
- C Anther
- D Style
Show answer
Correct answer: (C) Anther
The anther, at the tip of the stamen, produces pollen grains, which contain the male germ cells. The stigma, style and ovary are parts of the pistil, the female part of the flower.
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Q.241
Deficiency of Vitamin D in children causes
- A Scurvy
- B Rickets
- C Beri-beri
- D Pellagra
Show answer
Correct answer: (B) Rickets
Vitamin D (calciferol), made in the skin under sunlight, is needed to absorb calcium; its deficiency gives soft, bent bones (rickets) in children and osteomalacia in adults. Scurvy is due to vitamin C, beri-beri to B1 and pellagra to B3 deficiency.
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Q.242
The energy of the Sun and other stars is produced by
- A Nuclear fission
- B Chemical combustion
- C Nuclear fusion
- D Radioactive decay
Show answer
Correct answer: (C) Nuclear fusion
In the Sun, hydrogen nuclei fuse to form helium, releasing enormous energy (fusion). Nuclear reactors and the atom bomb use fission of uranium-235 or plutonium-239.
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Q.243
The frequency of the alternating current (AC) supplied to homes in India is
- A 25 Hz
- B 60 Hz
- C 100 Hz
- D 50 Hz
Show answer
Correct answer: (D) 50 Hz
Domestic AC in India has a frequency of 50 Hz, which means it changes direction 100 times every second. Some countries, such as the USA, use 60 Hz.
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Q.244
The odometer of a motor vehicle measures the
- A distance travelled by the vehicle
- B speed of the vehicle
- C acceleration of the vehicle
- D fuel consumed by the vehicle
Show answer
Correct answer: (A) distance travelled by the vehicle
An odometer records the total distance travelled by a vehicle. Its instantaneous speed is shown by the speedometer.
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Q.245
Cabbage, broccoli, cauliflower, kohlrabi and kale have all been developed from a single wild cabbage plant. This was brought about by
- A Natural selection
- B Artificial selection by farmers
- C Geographical isolation
- D Genetic drift
Show answer
Correct answer: (B) Artificial selection by farmers
Over generations, farmers chose and grew wild cabbage plants with the features they wanted, such as closely packed leaves, arrested flowers, swollen stems or larger leaves. This human-directed choice is artificial selection, not natural selection.
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Q.246
Rhizobium bacteria, which fix atmospheric nitrogen, live in the root nodules of
- A cereal plants such as wheat and rice
- B leguminous plants such as pea and gram
- C desert plants such as cactus
- D cone-bearing plants such as pine
Show answer
Correct answer: (B) leguminous plants such as pea and gram
Rhizobium lives in the root nodules of leguminous (pulse) plants such as pea, gram and beans and converts nitrogen gas into compounds the plant can use. This is why growing legumes improves soil fertility.
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Q.247
Heating a sulphide ore strongly in the presence of excess air to convert it into the metal oxide is called
- A Calcination
- B Smelting
- C Roasting
- D Electrolytic refining
Show answer
Correct answer: (C) Roasting
Roasting converts sulphide ores into oxides by strong heating in excess air, e.g. 2ZnS + 3O₂ → 2ZnO + 2SO₂. Calcination is heating carbonate ores strongly in limited air to change them into oxides.
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Q.248
The electronic configuration of calcium (atomic number 20) is
- A 2, 8, 10
- B 2, 8, 8, 2
- C 2, 8, 9, 1
- D 2, 10, 8
Show answer
Correct answer: (B) 2, 8, 8, 2
The K shell takes 2 electrons and the L shell 8; the M shell takes 8, after which the remaining 2 electrons enter the N shell, giving 2, 8, 8, 2. The outermost shell cannot hold more than 8 electrons, which rules out 2, 8, 10.
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Q.249
Pasteurisation, which protects milk from spoiling, involves
- A adding salt and sugar to the milk
- B heating the milk for a short time and then cooling it quickly
- C boiling the milk continuously for several hours
- D adding Lactobacillus to the milk
Show answer
Correct answer: (B) heating the milk for a short time and then cooling it quickly
In pasteurisation milk is heated for a short time and then suddenly chilled; this kills most harmful microbes and keeps the milk fresh for longer. The method is named after Louis Pasteur.
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Q.250
How many covalent bonds are present in one molecule of ethane (C₂H₆)?
- A 6
- B 7
- C 8
- D 9
Show answer
Correct answer: (B) 7
Ethane has one C-C single bond and six C-H single bonds, giving 1 + 6 = 7 covalent bonds.
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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.