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.51
The pH of normal human blood is about
- A 5.4
- B 6.4
- C 7.4
- D 8.4
Show answer
Correct answer: (C) 7.4
Blood is slightly alkaline, with a pH of 7.35 to 7.45. Gastric juice is strongly acidic (pH about 1.5 to 2), and pure water is neutral at pH 7.
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Q.52
Sound waves with a frequency below 20 Hz, such as those produced by elephants and whales, are called
- A Ultrasonic waves
- B Audible waves
- C Infrasonic waves
- D Supersonic waves
Show answer
Correct answer: (C) Infrasonic waves
Sound below 20 Hz is infrasonic (infrasound) and cannot be heard by humans. Ultrasonic waves are above 20,000 Hz, and 'supersonic' describes a speed greater than the speed of sound, not a frequency.
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Q.53
Soap is chemically the sodium or potassium salt of
- A Mineral acids
- B Long-chain fatty acids
- C Amino acids
- D Carbonic acid
Show answer
Correct answer: (B) Long-chain fatty acids
Soap is made by saponification of fats or oils with NaOH or KOH, giving sodium or potassium salts of fatty acids such as stearic acid, along with glycerol. Detergents are salts of sulphonic acids and work even in hard water.
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Q.54
In human beings, the sex of a child is determined by
- A the X chromosome received from the mother
- B whether the father's sperm carries an X or a Y chromosome
- C the mother's diet during pregnancy
- D the number of autosomes in the egg
Show answer
Correct answer: (B) whether the father's sperm carries an X or a Y chromosome
All eggs carry an X chromosome, while half the sperms carry X and half carry Y. A sperm with X gives a girl (XX) and a sperm with Y gives a boy (XY), so the father's chromosome decides the sex.
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Q.55
When a ship sails from a river into the sea, it
- A rises a little
- B sinks a little deeper
- C stays at exactly the same level
- D sinks completely
Show answer
Correct answer: (A) rises a little
Sea water is denser than river (fresh) water, so the ship needs to displace a smaller volume of sea water to balance its weight. Hence it rises a little.
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Q.56
The number of bones in an adult human body is
- A 206
- B 196
- C 212
- D 306
Show answer
Correct answer: (A) 206
An adult has 206 bones; a newborn has about 300, many of which fuse with age. The femur (thigh bone) is the longest and the stapes in the middle ear is the smallest bone.
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Q.57
A ball is thrown vertically upward with a speed of 20 m/s. Taking g = 10 m/s² and neglecting air resistance, the maximum height it reaches is
- A 10 m
- B 20 m
- C 40 m
- D 200 m
Show answer
Correct answer: (B) 20 m
At the highest point v = 0. Using v² = u² − 2gh: 0 = 20² − 2 × 10 × h, so h = 400/20 = 20 m.
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Q.58
Which of the following is a vector quantity?
- A Speed
- B Distance
- C Time
- D Velocity
Show answer
Correct answer: (D) Velocity
Velocity has both magnitude and direction, so it is a vector. Speed, distance and time have only magnitude and are scalars.
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Q.59
An object is placed at 2F (twice the focal length) in front of a convex lens. The image formed is
- A At F, real, inverted and highly diminished
- B Between F and 2F, real, inverted and diminished
- C Beyond 2F, real, inverted and magnified
- D At 2F on the other side, real, inverted and of the same size
Show answer
Correct answer: (D) At 2F on the other side, real, inverted and of the same size
For a convex lens, an object at 2F1 gives a real, inverted image of the same size at 2F2 on the other side. An object between F and 2F would give a magnified image beyond 2F, and an object beyond 2F a diminished image between F and 2F.
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Q.60
In humans, blood passes through the heart twice during each complete cycle of circulation. This is called
- A Double circulation
- B Single circulation
- C Open circulation
- D Portal circulation
Show answer
Correct answer: (A) Double circulation
Blood goes once from the heart to the lungs and back, and once from the heart to the rest of the body and back. This double circulation keeps oxygenated and deoxygenated blood separate; fishes have single circulation.
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Q.61
Which of the following elements exists as tetra-atomic molecules (four atoms per molecule)?
- A Phosphorus
- B Sulphur
- C Argon
- D Nitrogen
Show answer
Correct answer: (A) Phosphorus
Phosphorus exists as P₄ molecules. Sulphur exists as S₈ (polyatomic), argon is monoatomic and nitrogen is diatomic (N₂).
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Q.62
In a seed, the part that grows into the root when the seed germinates is the
- A Plumule
- B Cotyledon
- C Radicle
- D Seed coat
Show answer
Correct answer: (C) Radicle
The radicle is the future root and the plumule is the future shoot. Cotyledons store food for the growing embryo, and the seed coat protects the seed.
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Q.63
The enzyme present in saliva that begins the digestion of starch is
- A Pepsin
- B Trypsin
- C Lipase
- D Ptyalin
Show answer
Correct answer: (D) Ptyalin
Ptyalin (salivary amylase) converts starch into maltose in the mouth. Pepsin digests protein in the stomach, trypsin acts in the small intestine, and lipase breaks down fats.
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Q.64
Which of the following pairs of physical quantities have the same SI unit?
- A Work and power
- B Force and pressure
- C Work and energy
- D Speed and acceleration
Show answer
Correct answer: (C) Work and energy
Work and energy are both measured in joule (J). Power is measured in watt, force in newton, pressure in pascal, speed in m/s and acceleration in m/s².
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Q.65
An athlete runs exactly half a round of a circular track of radius 7 m. What is the magnitude of his displacement? (Take π = 22/7)
- A 22 m
- B 14 m
- C 44 m
- D 7 m
Show answer
Correct answer: (B) 14 m
Half a round takes him to the diametrically opposite point, so displacement = diameter = 2 × 7 = 14 m. The distance covered is πr = 22 m, and 44 m is one full round.
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Q.66
The main constituent of LPG (cooking gas) is
- A Methane
- B Butane
- C Ethane
- D Acetylene
Show answer
Correct answer: (B) Butane
LPG is mainly butane with some propane, liquefied under pressure; a foul-smelling compound (ethyl mercaptan) is added so that leaks can be detected. CNG and biogas are mainly methane.
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Q.67
Litmus, a commonly used natural acid-base indicator, is a purple dye extracted from
- A Turmeric
- B Lichen
- C Red cabbage leaves
- D Hydrangea flowers
Show answer
Correct answer: (B) Lichen
Litmus solution is a purple dye extracted from lichen (a partnership of a fungus with an alga, which NCERT places under Thallophyta). Turmeric, red cabbage leaves and the coloured petals of flowers such as hydrangea are other natural indicators, but litmus is not obtained from them.
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Q.68
When a drum is struck harder, its sound becomes louder because the
- A amplitude of vibration increases
- B frequency of vibration increases
- C speed of sound in air increases
- D wavelength of the sound decreases
Show answer
Correct answer: (A) amplitude of vibration increases
Striking harder makes the drum skin vibrate with a larger amplitude, and the loudness of a sound depends on its amplitude. The frequency (pitch) and the speed of sound in air do not change.
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Q.69
Which of the following is present in a plant cell but absent in an animal cell?
- A Cell wall
- B Cell membrane
- C Mitochondria
- D Ribosomes
Show answer
Correct answer: (A) Cell wall
Plant cells have a rigid cell wall, made mainly of cellulose, outside the cell membrane; animal cells lack it. Cell membrane, mitochondria and ribosomes are present in both.
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Q.70
Which statement about the value of g on the Earth's surface is correct?
- A It is the same at all places
- B It is greater at the equator than at the poles
- C It is zero at the poles
- D It is greater at the poles than at the equator
Show answer
Correct answer: (D) It is greater at the poles than at the equator
The Earth is slightly flattened at the poles, so the poles are closer to its centre than the equator is; since g = GM/R², g is greater at the poles. The Earth's rotation also slightly reduces g at the equator.
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Q.71
The structural and functional unit of the kidney is the
- A Nephron
- B Neuron
- C Alveolus
- D Villus
Show answer
Correct answer: (A) Nephron
Each kidney has about 10 lakh nephrons that filter blood and form urine. The neuron is the unit of the nervous system, the alveolus of the lung, and the villus is the absorbing finger-like projection in the small intestine.
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Q.72
Which non-metal exists as a liquid at room temperature?
- A Iodine
- B Chlorine
- C Bromine
- D Sulphur
Show answer
Correct answer: (C) Bromine
Bromine is the only non-metal that is a liquid at room temperature (mercury is the liquid metal). Chlorine is a gas, while iodine and sulphur are solids.
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Q.73
Which of the following is an example of Newton's third law of motion?
- A A rocket moves upward by pushing hot gases downward
- B Dust comes out of a carpet when it is beaten
- C Passengers fall backward when a bus starts suddenly
- D A ball rolling on the ground slowly comes to rest
Show answer
Correct answer: (A) A rocket moves upward by pushing hot gases downward
The rocket pushes the exhaust gases downward (action) and the gases push the rocket upward (reaction). Dust leaving a beaten carpet and passengers falling back are examples of inertia, and the rolling ball stops because of friction.
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Q.74
Which of the following is an unsaturated hydrocarbon?
- A Methane
- B Ethane
- C Propane
- D Ethene
Show answer
Correct answer: (D) Ethene
Ethene (C₂H₄) has a carbon-carbon double bond, so it is unsaturated. Methane, ethane and propane are alkanes, which have only single bonds and are saturated.
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Q.75
The image formed by a plane mirror is
- A Virtual, erect and of the same size as the object
- B Real, inverted and of the same size as the object
- C Virtual, erect and diminished
- D Real, erect and magnified
Show answer
Correct answer: (A) Virtual, erect and of the same size as the object
A plane mirror forms a virtual, erect, laterally inverted image of the same size as the object, as far behind the mirror as the object is in front of it.
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Q.76
Blood is classified as which type of tissue?
- A Epithelial tissue
- B Muscular tissue
- C Nervous tissue
- D Connective tissue
Show answer
Correct answer: (D) Connective tissue
Blood is a fluid connective tissue: its cells (red blood cells, white blood cells and platelets) are suspended in a liquid matrix called plasma, and it connects different parts of the body by transporting materials.
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Q.77
Stars appear to twinkle because of
- A Atmospheric refraction of starlight
- B Reflection of starlight by clouds
- C Dispersion of light inside the stars
- D Total internal reflection in the atmosphere
Show answer
Correct answer: (A) Atmospheric refraction of starlight
Starlight is refracted continuously by layers of air whose temperature and density keep changing, so the apparent position and brightness of a star keep flickering. Planets, being much closer, act as extended sources and do not twinkle.
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Q.78
The latent heat of fusion of ice is about
- A 3.34 x 10^5 J/kg
- B 2.25 x 10^6 J/kg
- C 4.2 x 10^3 J/kg
- D 3.34 x 10^3 J/kg
Show answer
Correct answer: (A) 3.34 x 10^5 J/kg
About 3.34 x 10^5 J of heat is needed to melt 1 kg of ice at 0 °C without changing its temperature. About 2.25 x 10^6 J/kg is the latent heat of vaporisation of water, and 4.2 x 10^3 J/kg °C is roughly the specific heat capacity of water.
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Q.79
Which of the following isotope-use pairs is correctly matched?
- A Cobalt-60 - treatment of cancer
- B Uranium-235 - treatment of goitre
- C Carbon-14 - fuel in nuclear reactors
- D Iodine-131 - finding the age of fossils and ancient wood
Show answer
Correct answer: (A) Cobalt-60 - treatment of cancer
A radioactive isotope of cobalt (cobalt-60) is used to treat cancer. An isotope of uranium is the fuel in nuclear reactors, an isotope of iodine is used to treat goitre, and carbon-14 is used to find the age of fossils and ancient wood.
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Q.80
The oxygen released during photosynthesis comes from
- A Carbon dioxide
- B Water
- C Glucose
- D Chlorophyll
Show answer
Correct answer: (B) Water
In the light reaction, water molecules are split (photolysis) and release oxygen; the carbon of carbon dioxide goes into glucose. This was proved using the heavy isotope oxygen-18.
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Q.81
A body of mass 2 kg has a momentum of 10 kg m/s. Its kinetic energy is
- A 25 J
- B 50 J
- C 100 J
- D 5 J
Show answer
Correct answer: (A) 25 J
Velocity v = p/m = 10/2 = 5 m/s, so KE = ½mv² = ½ × 2 × 5² = 25 J. (Equivalently, KE = p²/2m = 100/4 = 25 J.)
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Q.82
Steam at 100 °C causes more severe burns than boiling water at 100 °C because
- A Steam has a higher temperature than boiling water
- B Steam carries extra energy as the latent heat of vaporisation
- C Steam has a higher specific heat capacity than water
- D Steam particles are heavier than water particles
Show answer
Correct answer: (B) Steam carries extra energy as the latent heat of vaporisation
Both are at 100 °C, but each kilogram of steam holds additional energy equal to the latent heat of vaporisation, which it releases when it condenses on the skin. So steam delivers more heat than water at the same temperature.
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Q.83
The chemical name of Vitamin C is
- A Retinol
- B Thiamine
- C Ascorbic acid
- D Calciferol
Show answer
Correct answer: (C) Ascorbic acid
Vitamin C (ascorbic acid), found in citrus fruits and amla, prevents scurvy. Retinol is vitamin A, thiamine is vitamin B1 and calciferol is vitamin D.
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Q.84
How many structural isomers are possible for the molecular formula C₄H₁₀ (butane)?
- A 1
- B 2
- C 3
- D 4
Show answer
Correct answer: (B) 2
The molecular formula C₄H₁₀ has two structural isomers: straight-chain n-butane and branched isobutane (2-methylpropane). They have the same formula but different structures.
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Q.85
Newton's first law of motion is also known as the
- A Law of conservation of momentum
- B Law of action and reaction
- C Law of universal gravitation
- D Law of inertia
Show answer
Correct answer: (D) Law of inertia
The first law states that a body stays at rest or in uniform motion unless an external force acts on it; this tendency is inertia, so it is called the law of inertia. Action and reaction is the third law.
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Q.86
In tincture of iodine, used as an antiseptic, the solute and the solvent are respectively
- A Iodine and alcohol
- B Alcohol and iodine
- C Iodine and kerosene
- D Water and iodine
Show answer
Correct answer: (A) Iodine and alcohol
Tincture of iodine is a solution of iodine (the solute, present in the smaller amount) in alcohol (the solvent, present in the larger amount).
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Q.87
In Fleming's left-hand rule, the forefinger points in the direction of the magnetic field and the middle finger in the direction of the current. The thumb then points in the direction of
- A the induced current
- B the magnetic field lines
- C the force on (motion of) the conductor
- D the flow of electrons
Show answer
Correct answer: (C) the force on (motion of) the conductor
With the forefinger, middle finger and thumb of the left hand stretched mutually perpendicular, the forefinger along the field and the middle finger along the current, the thumb gives the direction of the force on the conductor. This rule explains how an electric motor works.
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Q.88
Which part of the human eye controls the size of the pupil?
- A Iris
- B Cornea
- C Retina
- D Ciliary muscles
Show answer
Correct answer: (A) Iris
The iris is a dark muscular diaphragm that changes the size of the pupil and so regulates the light entering the eye. The ciliary muscles change the curvature of the eye lens, and the image is formed on the retina.
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Q.89
Starfish and sea urchin, which are spiny-skinned marine animals, belong to the phylum
- A Mollusca
- B Echinodermata
- C Porifera
- D Arthropoda
Show answer
Correct answer: (B) Echinodermata
Echinoderms are spiny-skinned, exclusively free-living marine animals that move with the help of a water-driven tube system. Despite its name, a starfish is not a fish.
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Q.90
While ice is melting, its temperature stays at 0 °C even though heat is being supplied continuously. This is because the heat supplied is
- A Used to overcome the forces of attraction between the particles
- B Lost completely to the surroundings
- C Used to slow down the motion of the particles
- D Used to form new chemical bonds between water molecules
Show answer
Correct answer: (A) Used to overcome the forces of attraction between the particles
During a change of state the heat supplied (latent heat) is used to overcome the forces of attraction between particles instead of raising their kinetic energy, so the temperature does not rise until all the ice has melted. Melting is a physical change; no new chemical bonds form.
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Q.91
One atomic mass unit (1 u) is defined as
- A The mass of one hydrogen atom
- B 1/16 of the mass of one oxygen-16 atom
- C The mass of one proton
- D 1/12 of the mass of one carbon-12 atom
Show answer
Correct answer: (D) 1/12 of the mass of one carbon-12 atom
The carbon-12 atom is the accepted standard: 1 u is exactly one-twelfth of the mass of one atom of carbon-12. One-sixteenth of an oxygen atom was an older standard, and the mass of a proton is only approximately 1 u.
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Q.92
The binomial system of naming organisms was introduced by
- A Charles Darwin
- B Carolus Linnaeus
- C Ernst Haeckel
- D Aristotle
Show answer
Correct answer: (B) Carolus Linnaeus
The Swedish naturalist Carolus Linnaeus introduced the two-word (genus + species) system of scientific naming in the 18th century. Darwin is known for the theory of evolution by natural selection.
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Q.93
When resistors of different values are connected in series across a battery, which quantity is the same for every resistor?
- A Potential difference
- B Current
- C Heat produced
- D Power consumed
Show answer
Correct answer: (B) Current
A series circuit has only one path, so the same current flows through every resistor. The potential difference divides in proportion to the resistances, and so do the heat produced and the power (I^2R).
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Q.94
Kerosene rises in the wick of a lamp and ink spreads in blotting paper because of
- A Osmosis
- B Capillary action
- C Diffusion
- D Viscosity
Show answer
Correct answer: (B) Capillary action
Capillary action, caused by surface tension and adhesion, makes liquids rise in narrow tubes or pores; the same effect moves water up through soil and a towel.
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Q.95
The sea breeze during the day and the land breeze at night are caused by
- A conduction of heat through the air
- B convection currents in the air
- C reflection of heat by the sea
- D evaporation of sea water
Show answer
Correct answer: (B) convection currents in the air
By day the land heats up faster than the water; warm air over the land rises and cooler air from the sea moves in (sea breeze). At night the land cools faster and the flow reverses (land breeze). Both are convection currents.
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Q.96
During the manufacture of cement, a small amount of gypsum is added to the clinker. Its purpose is to
- A give the cement a grey colour
- B make the cement waterproof
- C speed up the setting of cement
- D slow down the setting of cement
Show answer
Correct answer: (D) slow down the setting of cement
Gypsum (CaSO₄·2H₂O) is ground with the cement clinker to slow down (regulate) the rate of setting, so that the cement does not harden too quickly to be worked after water is added.
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Q.97
Which of the following fuels has the highest calorific value?
- A Hydrogen
- B Coal
- C Petrol
- D LPG
Show answer
Correct answer: (A) Hydrogen
Hydrogen has the highest calorific value among common fuels, far higher than LPG, petrol or coal, and its only combustion product is water.
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Q.98
Which statement about connecting meters in an electric circuit is correct?
- A An ammeter is connected in parallel and a voltmeter in series
- B Both the ammeter and the voltmeter are connected in series
- C An ammeter is connected in series and a voltmeter in parallel
- D Both the ammeter and the voltmeter are connected in parallel
Show answer
Correct answer: (C) An ammeter is connected in series and a voltmeter in parallel
An ammeter measures the current through a component, so it is placed in series with it; a voltmeter measures the potential difference across a component, so it is connected in parallel with it.
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Q.99
The rings of cartilage present in the trachea (windpipe) ensure that
- A The air passage does not collapse
- B Food does not enter the air passage
- C Dust particles are filtered from the air
- D The inhaled air is warmed
Show answer
Correct answer: (A) The air passage does not collapse
The cartilage rings support the trachea and keep it open, so the air passage does not collapse. Entry of food into the windpipe is prevented by the epiglottis, and dust is trapped by the hairs and mucus of the nasal passage.
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Q.100
An atom has 3 electrons in its M shell, which is its outermost shell. Its atomic number is
- A 3
- B 11
- C 13
- D 15
Show answer
Correct answer: (C) 13
The K and L shells must be full (2 + 8), so the configuration is 2, 8, 3 and the atomic number is 2 + 8 + 3 = 13 (aluminium).
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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.