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.
Read the lesson on this topic →
← Previous Page 9 / 10 Next →
-
Q.401
Sound waves of frequency above which value are called ultrasonic?
- A 20 Hz
- B 200 Hz
- C 2,000 Hz
- D 20,000 Hz
Show answer
Correct answer: (D) 20,000 Hz
Humans hear roughly 20 Hz to 20,000 Hz. Frequencies above 20,000 Hz are ultrasonic (used in SONAR, by bats and in ultrasound scans); below 20 Hz they are infrasonic.
-
Q.402
The chemical name of bleaching powder is
- A Calcium oxychloride
- B Calcium carbonate
- C Calcium sulphate
- D Calcium hydroxide
Show answer
Correct answer: (A) Calcium oxychloride
Bleaching powder, CaOCl2, is made by passing chlorine over dry slaked lime and is used for bleaching cotton and disinfecting drinking water. Calcium hydroxide is slaked lime and calcium carbonate is limestone.
-
Q.403
A person suffering from acidity (indigestion caused by too much acid in the stomach) is usually given an antacid such as
- A Milk of magnesia
- B Vinegar
- C Lemon juice
- D Dilute hydrochloric acid
Show answer
Correct answer: (A) Milk of magnesia
Milk of magnesia is magnesium hydroxide, a mild base that neutralises the excess hydrochloric acid in the stomach. Vinegar, lemon juice and hydrochloric acid are themselves acidic and would make the acidity worse.
-
Q.404
Trypsin, an enzyme that digests proteins, is secreted by the
- A Gastric glands of the stomach
- B Salivary glands
- C Pancreas
- D Liver
Show answer
Correct answer: (C) Pancreas
The pancreas pours pancreatic juice, containing trypsin for proteins and lipase for emulsified fats, into the small intestine. The gastric glands secrete pepsin, the salivary glands secrete salivary amylase, and the liver secretes bile.
-
Q.405
Milk is turned into curd by the action of
- A Rhizobium
- B Yeast
- C Penicillium
- D Lactobacillus
Show answer
Correct answer: (D) Lactobacillus
Lactobacillus bacteria multiply in milk and convert the milk sugar into lactic acid, which sets the milk into curd. Yeast is a fungus used in baking and Penicillium is a mould.
-
Q.406
Sodium has atomic number 11 and electronic configuration 2, 8, 1. Its valency is
- A 1
- B 2
- C 3
- D 8
Show answer
Correct answer: (A) 1
Valency is the combining capacity decided by the outermost electrons. Sodium loses its single valence electron to attain the stable octet of neon, so its valency is 1.
-
Q.407
Which of the following disease - causal organism pairs is correctly matched?
- A Typhoid - Virus
- B Chickenpox - Bacterium
- C Ringworm - Fungus
- D Polio - Protozoan
Show answer
Correct answer: (C) Ringworm - Fungus
Ringworm is a fungal infection of the skin. Typhoid is caused by a bacterium, while chickenpox and polio are caused by viruses.
-
Q.408
Which of the following is a neutralisation reaction?
- A NaOH + HCl → NaCl + H₂O
- B Zn + H₂SO₄ → ZnSO₄ + H₂
- C CaCO₃ → CaO + CO₂
- D 2Mg + O₂ → 2MgO
Show answer
Correct answer: (A) NaOH + HCl → NaCl + H₂O
In neutralisation an acid reacts with a base to form a salt and water, as hydrochloric acid and sodium hydroxide do here. The other three are a displacement, a decomposition and a combination reaction respectively.
-
Q.409
Which of the following statements about lenses is correct?
- A A concave lens always forms a real image
- B The power of a concave lens is negative
- C A convex lens always forms a virtual image
- D A lens with a shorter focal length has a lower power
Show answer
Correct answer: (B) The power of a concave lens is negative
A concave lens has a negative focal length, so its power (1/f) is negative. A concave lens forms only virtual images of real objects, a convex lens forms real images for most object positions, and a shorter focal length means a higher power.
-
Q.410
In a homologous series, two successive members differ by a –CH₂– unit. By how much do their molecular masses differ?
- A 12 u
- B 13 u
- C 14 u
- D 16 u
Show answer
Correct answer: (C) 14 u
A CH₂ unit has a mass of 12 u + 2 × 1 u = 14 u, so successive members such as methane (16 u) and ethane (30 u) differ by 14 u.
-
Q.411
The sting of an ant and the stinging hair of a nettle leaf inject which acid into the skin?
- A Citric acid
- B Lactic acid
- C Oxalic acid
- D Methanoic acid
Show answer
Correct answer: (D) Methanoic acid
Ant and nettle stings contain methanoic acid (formic acid), which causes pain and irritation. Citric acid is found in lemons and lactic acid in curd.
-
Q.412
Four solutions P, Q, R and S have pH values of 4, 1, 11 and 7 respectively. Which solution has the highest concentration of hydrogen ions?
- A P
- B Q
- C R
- D S
Show answer
Correct answer: (B) Q
The lower the pH, the higher the hydrogen ion concentration. Q (pH 1) is the most strongly acidic; P is weakly acidic, S is neutral and R is basic.
-
Q.413
Night blindness is caused by the deficiency of
- A Vitamin B1
- B Vitamin C
- C Vitamin A
- D Vitamin K
Show answer
Correct answer: (C) Vitamin A
Vitamin A is needed to make the light-sensitive pigment of the retina, and its deficiency causes night blindness, that is, difficulty in seeing in dim light. Carrots, green leafy vegetables, milk and fish-liver oil are good sources.
-
Q.414
In the human lungs, the exchange of gases between air and blood takes place in the
- A Trachea
- B Bronchi
- C Bronchioles
- D Alveoli
Show answer
Correct answer: (D) Alveoli
The bronchioles end in tiny balloon-like sacs called alveoli, whose thin walls are covered by a network of blood capillaries; oxygen and carbon dioxide are exchanged here. The trachea, bronchi and bronchioles only conduct air.
-
Q.415
The inner walls of a thermos flask are silvered to prevent loss of heat by
- A Conduction
- B Convection
- C Radiation
- D Evaporation
Show answer
Correct answer: (C) Radiation
Silvered surfaces reflect radiant heat back, cutting loss by radiation. The vacuum between the double walls stops conduction and convection, and the cork lid reduces loss through the mouth.
-
Q.416
At which temperature do the Celsius and Fahrenheit scales show the same reading?
- A -40 degrees
- B 0 degrees
- C 32 degrees
- D 100 degrees
Show answer
Correct answer: (A) -40 degrees
Using F = 9C/5 + 32 and putting F = C gives C = -40, so -40 degrees C equals -40 degrees F. 0 degrees C is 32 degrees F and 100 degrees C is 212 degrees F.
-
Q.417
A leaf from a plant kept in sunlight is boiled in alcohol and then a few drops of iodine solution are put on it. The leaf turns blue-black. This shows the presence of
- A Starch
- B Glucose
- C Protein
- D Chlorophyll
Show answer
Correct answer: (A) Starch
Iodine gives a blue-black colour with starch. Boiling in alcohol removes the chlorophyll so that the colour can be seen; the starch shows that the leaf made food by photosynthesis and stored the extra as starch.
-
Q.418
Bryophyllum can be propagated vegetatively by buds produced in the notches along the margins of its
- A Roots
- B Leaves
- C Flowers
- D Stems
Show answer
Correct answer: (B) Leaves
Buds formed in the notches along the leaf margins of Bryophyllum fall on the soil and grow into new plants. This is a form of vegetative propagation.
-
Q.419
The SI unit of force is the
- A joule
- B watt
- C newton
- D pascal
Show answer
Correct answer: (C) newton
Force = mass × acceleration, so its SI unit is kg m/s², called the newton (N). The joule is the unit of work and energy, the watt of power and the pascal of pressure.
-
Q.420
Newlands' Law of Octaves, under which every eighth element had properties similar to those of the first, was found to work well only up to
- A Calcium
- B Argon
- C Iron
- D Uranium
Show answer
Correct answer: (A) Calcium
Newlands' arrangement worked only for the lighter elements up to calcium; after calcium, every eighth element did not show properties similar to the first. He compared the pattern to the octaves of music.
-
Q.421
As we go higher above sea level, the atmospheric pressure
- A increases
- B decreases
- C remains the same
- D first decreases and then increases
Show answer
Correct answer: (B) decreases
Atmospheric pressure is caused by the weight of the air above us. At greater heights there is less air above, so the pressure decreases.
-
Q.422
A body is moving with a constant velocity along a straight line. The net force acting on it is
- A zero
- B equal to its weight
- C in the direction of motion
- D opposite to the direction of motion
Show answer
Correct answer: (A) zero
By Newton's first law, a body keeps moving with uniform velocity in a straight line when the net (unbalanced) force on it is zero. Any net force would change its velocity.
-
Q.423
The Doppler effect refers to the
- A Apparent change in frequency of a wave due to relative motion of source and observer
- B Bending of sound waves around the corner of a building
- C Reflection of sound from a distant wall
- D Splitting of white light into seven colours
Show answer
Correct answer: (A) Apparent change in frequency of a wave due to relative motion of source and observer
When a source and observer approach each other the observed frequency rises (an approaching siren sounds higher), and it falls as they move apart. Bending around corners is diffraction and splitting into colours is dispersion.
-
Q.424
Natural chlorine contains two isotopes, chlorine-35 and chlorine-37, in the ratio 3 : 1. The average atomic mass of chlorine is
- A 36.0 u
- B 35.0 u
- C 35.5 u
- D 36.5 u
Show answer
Correct answer: (C) 35.5 u
Average atomic mass = (35 x 3/4) + (37 x 1/4) = 26.25 + 9.25 = 35.5 u. This is why the atomic mass of chlorine is not a whole number.
-
Q.425
Which of the following plants bears unisexual flowers, that is, flowers having either stamens or a pistil but not both?
- A Maize
- B Hibiscus
- C Mustard
- D Pea
Show answer
Correct answer: (A) Maize
Maize has unisexual flowers: the male flowers are borne in the tassel at the top of the plant and the female flowers on the cob (ear) lower down. Hibiscus, mustard and pea have bisexual flowers that contain both stamens and a pistil.
-
Q.426
Which of the following is an important role of transpiration in plants?
- A It produces glucose for the plant
- B It creates a suction pull that helps draw water upwards through the xylem
- C It carries food from the leaves to the roots
- D It fixes nitrogen from the air
Show answer
Correct answer: (B) It creates a suction pull that helps draw water upwards through the xylem
As water evaporates from the leaves, more water is pulled up through the xylem; this suction moves water and dissolved minerals upwards from the roots. Transpiration also helps in regulating the temperature of the plant.
-
Q.427
A body is taken from the Earth to the Moon. Which statement is correct?
- A Its mass decreases but its weight remains the same
- B Its mass remains the same but its weight becomes about one-sixth
- C Both mass and weight remain unchanged
- D Both mass and weight become one-sixth
Show answer
Correct answer: (B) Its mass remains the same but its weight becomes about one-sixth
Mass is the quantity of matter and does not change with place. Weight = mg depends on gravity, and the Moon's g is about one-sixth of the Earth's.
-
Q.428
A block of wood of density 600 kg/m³ floats in water (density 1000 kg/m³). What fraction of its volume remains under water?
- A 40%
- B 50%
- C 100%
- D 60%
Show answer
Correct answer: (D) 60%
For a floating body, weight = buoyant force, so V × 600 × g = V' × 1000 × g, where V' is the submerged volume. Hence V'/V = 600/1000 = 0.6, i.e. 60% is under water and 40% stays above.
-
Q.429
Which part of the brain controls involuntary actions such as blood pressure, salivation and vomiting?
- A Cerebrum
- B Cerebellum
- C Medulla
- D Olfactory lobe
Show answer
Correct answer: (C) Medulla
The medulla (medulla oblongata) of the hind-brain controls involuntary actions like blood pressure, salivation and vomiting. The cerebellum, also in the hind-brain, controls posture and balance, while the cerebrum is the main thinking part of the fore-brain.
-
Q.430
The kinetic energy of a body of mass 2 kg moving with a velocity of 3 m/s is
- A 6 J
- B 9 J
- C 18 J
- D 3 J
Show answer
Correct answer: (B) 9 J
KE = ½mv² = ½ × 2 × 3² = 9 J. The answer 18 J comes from forgetting the ½, and 6 is the value of the momentum mv (in kg m/s), not the kinetic energy.
-
Q.431
Zinc is more reactive than iron, and iron is more reactive than copper. Which of the following reactions will NOT take place?
- A Fe + CuSO₄ → FeSO₄ + Cu
- B Zn + CuSO₄ → ZnSO₄ + Cu
- C Zn + FeSO₄ → ZnSO₄ + Fe
- D Cu + FeSO₄ → CuSO₄ + Fe
Show answer
Correct answer: (D) Cu + FeSO₄ → CuSO₄ + Fe
A metal can displace only a less reactive metal from a solution of its salt. Copper is less reactive than iron, so it cannot displace iron from iron sulphate; the other three reactions do take place.
-
Q.432
Which of the following is a thermosetting plastic that does not soften on heating and is therefore used to make electrical switches and handles of cooking utensils?
- A Polythene
- B PVC
- C Bakelite
- D Polystyrene
Show answer
Correct answer: (C) Bakelite
Bakelite is a thermosetting plastic: once moulded it does not soften on heating, and it is a poor conductor of heat and electricity. Polythene, PVC and polystyrene are thermoplastics, which soften on heating.
-
Q.433
A mixture of kerosene and water can be separated using a
- A Sieve
- B Filter paper
- C Separating funnel
- D Magnet
Show answer
Correct answer: (C) Separating funnel
Kerosene and water are immiscible and form separate layers, kerosene floating on top because it is less dense. Opening the stopcock of a separating funnel lets the lower water layer run out first.
-
Q.434
The loudness (sound level) of a sound is commonly expressed in
- A Hertz
- B Decibel
- C Pascal
- D Joule
Show answer
Correct answer: (B) Decibel
Sound level is measured in decibels (dB). Hertz is the unit of frequency, pascal of pressure and joule of energy.
-
Q.435
Mendeleev arranged the elements in his periodic table mainly on the basis of their
- A Atomic number
- B Atomic mass
- C Number of neutrons
- D Electronic configuration
Show answer
Correct answer: (B) Atomic mass
Mendeleev arranged the elements in increasing order of atomic mass and grouped them by similar properties, such as the formulae of their oxides and hydrides. Atomic number became the basis only in the modern periodic table.
-
Q.436
In graphite, each carbon atom is bonded to how many other carbon atoms in the same layer?
- A 1
- B 2
- C 3
- D 4
Show answer
Correct answer: (C) 3
In graphite each carbon atom is bonded to three other carbon atoms in the same plane, giving a hexagonal array; one of these bonds is a double bond, which satisfies carbon's valency of four. In diamond, each carbon atom is bonded to four others.
-
Q.437
The number of chromosomes in a normal human body (somatic) cell is
- A 23
- B 44
- C 48
- D 46
Show answer
Correct answer: (D) 46
Human somatic cells have 46 chromosomes (23 pairs), of which one pair (XX in females, XY in males) determines sex. Gametes (sperm and ovum) carry 23 chromosomes each.
-
Q.438
Metals high up in the reactivity series, such as sodium, calcium and aluminium, are obtained from their compounds by
- A heating their oxides with carbon
- B electrolysis of their molten chlorides or oxides
- C heating their ores alone in air
- D displacement from their salt solutions by copper
Show answer
Correct answer: (B) electrolysis of their molten chlorides or oxides
These metals have more affinity for oxygen than carbon has, so carbon cannot reduce their oxides. They are obtained by electrolytic reduction of their molten compounds, e.g. sodium from molten sodium chloride; copper is less reactive and cannot displace them.
-
Q.439
Which statement about the folding of the leaves of the 'touch-me-not' (Mimosa pudica) plant when it is touched is correct?
- A It is a growth movement caused by auxin
- B It is an example of phototropism
- C It happens because cells change shape by changing the amount of water in them
- D It takes several days to complete
Show answer
Correct answer: (C) It happens because cells change shape by changing the amount of water in them
The leaves of the sensitive plant fold within moments of being touched, without any growth. Plant cells change shape by changing the amount of water in them, so the leaves shrink and fold; this is not a growth-related tropism.
-
Q.440
Which plant hormone is responsible for the ripening of fruits?
- A Auxin
- B Gibberellin
- C Ethylene
- D Cytokinin
Show answer
Correct answer: (C) Ethylene
Ethylene, a gaseous hormone, hastens ripening, which is why one ripe banana ripens others kept with it. Auxin causes cell elongation and bending towards light, gibberellin stem growth and cytokinin cell division.
-
Q.441
The testes of human males lie outside the abdominal cavity, in the scrotum, because
- A they need more space than the abdomen can provide
- B sperm formation requires a temperature lower than normal body temperature
- C they need to be close to the urinary bladder
- D this protects them better from injury
Show answer
Correct answer: (B) sperm formation requires a temperature lower than normal body temperature
Sperms are formed in the testes, and their formation needs a temperature slightly lower than normal body temperature. Keeping the testes in the scrotum, outside the abdomen, provides this.
-
Q.442
If the velocity of a body is doubled, its kinetic energy becomes
- A double
- B half
- C four times
- D unchanged
Show answer
Correct answer: (C) four times
KE = ½mv² depends on the square of the velocity, so doubling v makes the kinetic energy 2² = 4 times.
-
Q.443
The filament of an incandescent electric bulb is made of tungsten mainly because tungsten
- A is a magnetic metal
- B is the lightest metal
- C has a low melting point
- D has a very high melting point
Show answer
Correct answer: (D) has a very high melting point
The filament must glow white-hot without melting, and tungsten has a very high melting point. Bulbs are filled with chemically inactive gases such as argon or nitrogen to prolong the life of the filament.
-
Q.444
Mendel crossed pure tall pea plants with pure dwarf pea plants and all the F1 plants were tall. When the F1 plants were self-pollinated, the ratio of tall to dwarf plants in the F2 generation was
- A 1 : 1
- B 1 : 3
- C 2 : 1
- D 3 : 1
Show answer
Correct answer: (D) 3 : 1
The F1 plants are Tt. Selfing Tt × Tt gives TT, Tt, Tt and tt with equal chances; the first three are tall because T is dominant, so tall : dwarf = 3 : 1.
-
Q.445
Which allotrope of carbon is a good conductor of electricity?
- A Diamond
- B Graphite
- C Fullerene
- D Charcoal
Show answer
Correct answer: (B) Graphite
In graphite each carbon atom bonds to only three others, leaving one free electron per atom to conduct electricity, which is why graphite is used as electrodes. In diamond all four electrons are bonded, so it is an insulator.
-
Q.446
Galvanisation is the process of coating iron or steel with a thin layer of
- A Tin
- B Zinc
- C Chromium
- D Nickel
Show answer
Correct answer: (B) Zinc
Zinc is more reactive than iron and keeps protecting it even when the coating is scratched, so galvanised sheets resist rusting. Tin-plating is used for food cans.
-
Q.447
Small gaps are left at the joints between the rails of a railway track because
- A the rails contract in summer and need room to move
- B the gaps reduce the noise of moving trains
- C the gaps let rainwater drain off the track
- D the rails expand when heated, and the gaps leave room for this expansion in summer
Show answer
Correct answer: (D) the rails expand when heated, and the gaps leave room for this expansion in summer
Steel rails expand when they are heated (thermal expansion). The small gaps left at the joints give the rails room to expand on hot summer days; without them the rails would push against each other and could bend out of shape. The gaps do not reduce noise: the familiar clicking of a train is made as its wheels pass over them.
-
Q.448
Hydrogen gas is not usually evolved when a metal reacts with nitric acid. This is because nitric acid
- A is a weak acid
- B is a strong oxidising agent that oxidises the hydrogen produced to water
- C does not contain hydrogen
- D does not react with any metal
Show answer
Correct answer: (B) is a strong oxidising agent that oxidises the hydrogen produced to water
HNO₃ is a strong oxidising agent: it oxidises the H₂ formed to water and is itself reduced to oxides of nitrogen such as N₂O, NO or NO₂. Only magnesium and manganese give hydrogen with very dilute nitric acid.
-
Q.449
When a moving bus stops suddenly, the standing passengers tend to fall forward. This is due to
- A inertia of rest
- B inertia of motion
- C Newton's third law of motion
- D the force of gravity
Show answer
Correct answer: (B) inertia of motion
The bus, and the passengers' feet in contact with it, stop, but their bodies tend to keep moving forward (inertia of motion). When a bus starts suddenly, passengers fall backward due to inertia of rest.
-
Q.450
Ethanoic acid reacts with ethanol in the presence of a few drops of concentrated sulphuric acid to form a sweet-smelling substance. This reaction is called
- A Saponification
- B Esterification
- C Fermentation
- D Hydrogenation
Show answer
Correct answer: (B) Esterification
An acid and an alcohol react to form an ester (here ethyl ethanoate) and water: CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O. This is esterification; esters are used in perfumes and as flavouring agents.
← Previous Page 9 / 10 Next →
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.