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.101
Which of the following diseases is caused by a bacterium?
- A Tuberculosis
- B Polio
- C Measles
- D Rabies
Show answer
Correct answer: (A) Tuberculosis
Tuberculosis is caused by Mycobacterium tuberculosis, discovered by Robert Koch; BCG is its vaccine. Polio, measles and rabies are all viral diseases.
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Q.102
A gene, the unit of inheritance, is a section of
- A DNA
- B Protein
- C Ribosome
- D Cell membrane
Show answer
Correct answer: (A) DNA
A gene is a section of DNA on a chromosome that carries the information for making a particular protein. Proteins are made using this information, and ribosomes are where they are made.
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Q.103
The path of a beam of sunlight entering a dark, dusty room through a small hole becomes visible because of
- A Total internal reflection
- B Dispersion of light
- C The Tyndall effect
- D Atmospheric refraction
Show answer
Correct answer: (C) The Tyndall effect
Tiny dust and smoke particles in the room scatter the light sideways, making the beam visible. Scattering of light by such fine (colloidal) particles is called the Tyndall effect.
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Q.104
The branch of biology that deals with the study of insects is
- A Entomology
- B Ornithology
- C Ichthyology
- D Herpetology
Show answer
Correct answer: (A) Entomology
Entomology is the study of insects. Ornithology deals with birds, ichthyology with fishes, and herpetology with reptiles and amphibians.
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Q.105
The thermite reaction, used to join broken railway tracks and cracked machine parts, is the reaction of iron(III) oxide with
- A Aluminium
- B Carbon
- C Zinc
- D Copper
Show answer
Correct answer: (A) Aluminium
Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat. Aluminium is more reactive than iron, and the reaction is so exothermic that the iron is produced in the molten state, which is used for welding.
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Q.106
The SI unit of momentum is
- A kg m/s²
- B kg m²/s
- C kg m/s
- D J/s
Show answer
Correct answer: (C) kg m/s
Momentum p = mass × velocity, so its unit is kg × m/s = kg m/s (equivalently N s). kg m/s² is the newton, the unit of force, and J/s is the watt.
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Q.107
Which component of blood helps the blood to clot at the site of an injury?
- A Red blood cells
- B Platelets
- C White blood cells
- D Haemoglobin
Show answer
Correct answer: (B) Platelets
Platelets circulate in the blood and help it to clot at the point of injury, plugging the leak and preventing loss of blood. Red blood cells carry oxygen and white blood cells fight infection.
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Q.108
How many moles are present in 36 g of water (H₂O)? (H = 1 u, O = 16 u)
- A 1 mol
- B 2 mol
- C 0.5 mol
- D 18 mol
Show answer
Correct answer: (B) 2 mol
Molar mass of H₂O = 2(1) + 16 = 18 g/mol. Number of moles = 36 g / 18 g/mol = 2 mol.
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Q.109
A yellow turmeric (curry) stain on a white cloth turns reddish-brown when soap is scrubbed on it, and becomes yellow again when the cloth is rinsed with plenty of water. This shows that soap solution is
- A Weakly acidic
- B Strongly acidic
- C Neutral
- D Basic
Show answer
Correct answer: (D) Basic
Turmeric is a natural indicator that turns reddish-brown in a basic medium. Soap solution is basic, so the stain turns reddish-brown; rinsing washes the soap away and the yellow colour returns.
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Q.110
Which nutrient provides the most energy per gram?
- A Carbohydrates
- B Fats
- C Proteins
- D Vitamins
Show answer
Correct answer: (B) Fats
Fats give about 9 kilocalories per gram, more than twice the roughly 4 kilocalories per gram given by carbohydrates or proteins. Vitamins give no energy but are needed in small amounts for good health.
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Q.111
Baking soda, used in cooking and in soda-acid fire extinguishers, is chemically
- A Sodium carbonate
- B Sodium hydroxide
- C Sodium chloride
- D Sodium hydrogen carbonate
Show answer
Correct answer: (D) Sodium hydrogen carbonate
Baking soda is NaHCO3 (sodium bicarbonate). Washing soda is sodium carbonate (Na2CO3.10H2O) and caustic soda is sodium hydroxide (NaOH).
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Q.112
Sieve tubes and companion cells are components of which plant tissue?
- A Xylem
- B Phloem
- C Collenchyma
- D Epidermis
Show answer
Correct answer: (B) Phloem
Phloem is made of sieve tubes, companion cells, phloem parenchyma and phloem fibres, and carries food from the leaves to other parts of the plant. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres.
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Q.113
The vaccine against smallpox, the first vaccine in history, was developed by
- A Louis Pasteur
- B Alexander Fleming
- C Edward Jenner
- D Robert Koch
Show answer
Correct answer: (C) Edward Jenner
Edward Jenner used cowpox material in 1796 to protect against smallpox, which has since been eradicated worldwide. Pasteur developed the rabies vaccine and Fleming discovered penicillin.
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Q.114
The value of the acceleration due to gravity (g) at the centre of the Earth is
- A zero
- B 9.8 m/s²
- C maximum
- D infinite
Show answer
Correct answer: (A) zero
The value of g decreases as we go deeper inside the Earth and becomes zero at its centre, where the pull of the Earth's mass from all sides cancels out.
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Q.115
Bags of potato chips are flushed with nitrogen gas. This prevents the fats and oils in the chips from
- A Getting oxidised and turning rancid
- B Getting reduced
- C Getting hydrogenated
- D Getting neutralised
Show answer
Correct answer: (A) Getting oxidised and turning rancid
When fats and oils are oxidised, their smell and taste change; this is called rancidity. Nitrogen, an unreactive gas, replaces the oxygen in the bag and so slows down this oxidation.
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Q.116
In Mendel's dihybrid cross between pea plants having round yellow seeds and plants having wrinkled green seeds, the phenotypic ratio obtained in the F2 generation was
- A 3 : 1
- B 1 : 2 : 1
- C 9 : 3 : 3 : 1
- D 1 : 1 : 1 : 1
Show answer
Correct answer: (C) 9 : 3 : 3 : 1
In F2 Mendel got round yellow, round green, wrinkled yellow and wrinkled green seeds in the ratio 9 : 3 : 3 : 1, showing that the two traits are inherited independently. 3 : 1 is the monohybrid phenotypic ratio and 1 : 2 : 1 the monohybrid genotypic ratio.
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Q.117
When a beam of light is passed through each of the following, in which will the path of the beam become visible (Tyndall effect)?
- A Salt solution
- B Sugar solution
- C Copper sulphate solution
- D Milk
Show answer
Correct answer: (D) Milk
Milk is a colloid; its particles are big enough to scatter light, making the path of the beam visible. Salt, sugar and copper sulphate solutions are true solutions, whose tiny particles do not scatter light.
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Q.118
A car moving at 20 m/s is brought to rest uniformly in 4 s by applying the brakes. The magnitude of its retardation is
- A 5 m/s²
- B 80 m/s²
- C 0.2 m/s²
- D 16 m/s²
Show answer
Correct answer: (A) 5 m/s²
a = (v − u)/t = (0 − 20)/4 = −5 m/s². The negative sign shows retardation, whose magnitude is 5 m/s².
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Q.119
The enzyme pepsin, secreted in the stomach, acts on
- A Starch
- B Fats
- C Proteins
- D Cellulose
Show answer
Correct answer: (C) Proteins
Pepsin is the protein-digesting enzyme of the gastric juice and works in the acidic medium created by hydrochloric acid. Starch is acted on by amylase and fats by lipase, while humans cannot digest cellulose.
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Q.120
At a given temperature, the resistance of a metallic wire is directly proportional to its length and inversely proportional to
- A the current flowing through it
- B its area of cross-section
- C the potential difference across it
- D its resistivity
Show answer
Correct answer: (B) its area of cross-section
R = ρl/A: resistance rises with length, falls as the wire gets thicker (larger area of cross-section) and is directly proportional to resistivity. It does not depend on the current or the potential difference applied.
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Q.121
Which of the following is NOT a unit of energy?
- A joule
- B calorie
- C electron volt
- D watt
Show answer
Correct answer: (D) watt
The watt (J/s) is a unit of power, the rate of doing work. The joule, calorie and electron volt are all units of energy.
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Q.122
The valency of aluminium is 3 and that of the sulphate ion is 2. The chemical formula of aluminium sulphate is
- A AlSO₄
- B Al₃(SO₄)₂
- C Al₂(SO₄)₃
- D Al(SO₄)₃
Show answer
Correct answer: (C) Al₂(SO₄)₃
Crossing over the valencies of Al³⁺ and SO₄²⁻ gives Al₂(SO₄)₃: two aluminium ions carry 6 positive charges, balanced by three sulphate ions carrying 6 negative charges.
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Q.123
Ordinary (soda-lime) glass is made by melting together sand (silica), sodium carbonate and
- A Calcium carbonate (limestone)
- B Copper sulphate
- C Sodium chloride
- D Ammonium nitrate
Show answer
Correct answer: (A) Calcium carbonate (limestone)
Soda-lime glass, used for windows and bottles, is made by fusing silica (SiO₂) with sodium carbonate and calcium carbonate at a high temperature. It is mainly a mixture of sodium and calcium silicates.
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Q.124
The element that Mendeleev called 'eka-aluminium', and whose properties he predicted before it was discovered, is now known as
- A Scandium
- B Germanium
- C Gallium
- D Aluminium
Show answer
Correct answer: (C) Gallium
Eka-aluminium was later discovered as gallium, with properties very close to Mendeleev's predictions. Eka-boron turned out to be scandium and eka-silicon germanium.
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Q.125
Which of the following is a genetic (hereditary) disorder and not an infectious disease?
- A Typhoid
- B Cholera
- C Malaria
- D Haemophilia
Show answer
Correct answer: (D) Haemophilia
Haemophilia, in which blood fails to clot normally, is a sex-linked genetic disorder carried on the X chromosome; colour blindness, sickle-cell anaemia and Down syndrome are other genetic conditions. Typhoid and cholera are bacterial and malaria is protozoan.
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Q.126
Ozone (O₃) in the upper atmosphere is formed when
- A ultraviolet radiation splits O₂ molecules into oxygen atoms, which then combine with other O₂ molecules
- B carbon dioxide reacts with water vapour in sunlight
- C nitrogen and oxygen combine during lightning
- D CFC molecules combine with oxygen
Show answer
Correct answer: (A) ultraviolet radiation splits O₂ molecules into oxygen atoms, which then combine with other O₂ molecules
High-energy UV radiation splits some O₂ molecules into free oxygen atoms (O); each atom then joins an O₂ molecule to form ozone, O₃. Lightning makes nitrogen and oxygen combine into oxides of nitrogen, and CFCs destroy ozone rather than form it.
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Q.127
A clinical thermometer usually has a range of
- A 35 °C to 42 °C
- B 0 °C to 100 °C
- C -10 °C to 110 °C
- D 20 °C to 50 °C
Show answer
Correct answer: (A) 35 °C to 42 °C
Human body temperature normally stays within a narrow range, so a clinical thermometer reads only from about 35 °C to 42 °C. A laboratory thermometer usually has a range of -10 °C to 110 °C.
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Q.128
The mass of 0.5 mole of nitrogen gas (N₂) is (atomic mass of N = 14 u)
- A 28 g
- B 7 g
- C 56 g
- D 14 g
Show answer
Correct answer: (D) 14 g
Molar mass of N₂ = 2 x 14 = 28 g/mol, so 0.5 mol has a mass of 0.5 x 28 = 14 g. Taking 0.5 mole of N atoms instead of N₂ molecules would wrongly give 7 g.
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Q.129
The electron was discovered by
- A Ernest Rutherford
- B J.J. Thomson
- C James Chadwick
- D E. Goldstein
Show answer
Correct answer: (B) J.J. Thomson
J.J. Thomson discovered the electron while studying cathode rays. Goldstein discovered canal rays, Rutherford discovered the nucleus and Chadwick discovered the neutron.
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Q.130
According to Newton's second law of motion, the force acting on a body is proportional to the
- A rate of change of its momentum
- B change in its position
- C mass of the body only
- D rate of change of its displacement
Show answer
Correct answer: (A) rate of change of its momentum
The second law states that the rate of change of momentum of a body is proportional to the applied force and takes place in the direction of the force. For constant mass this gives F = ma.
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Q.131
The right-hand thumb rule is used to find the
- A direction of the force on a current-carrying conductor placed in a magnetic field
- B direction of the magnetic field around a straight current-carrying conductor
- C direction of the induced current in a generator
- D magnitude of the current in a conductor
Show answer
Correct answer: (B) direction of the magnetic field around a straight current-carrying conductor
If a straight conductor is held in the right hand with the thumb along the current, the curled fingers show the direction of the magnetic field lines, which are concentric circles around the wire. The force on a conductor is given by Fleming's left-hand rule and the induced current by Fleming's right-hand rule.
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Q.132
Which non-metal is stored under water because it catches fire when exposed to air?
- A Sulphur
- B White phosphorus
- C Iodine
- D Carbon
Show answer
Correct answer: (B) White phosphorus
White phosphorus is very reactive and catches fire on exposure to air, so it is kept under water to prevent contact with atmospheric oxygen. Sulphur, iodine and carbon do not ignite on their own in air.
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Q.133
The hormone insulin, whose deficiency causes diabetes mellitus, is secreted by the
- A Liver
- B Pancreas
- C Thyroid gland
- D Adrenal gland
Show answer
Correct answer: (B) Pancreas
The beta cells of the islets of Langerhans in the pancreas secrete insulin, which lowers blood glucose. The thyroid secretes thyroxine and the adrenal glands secrete adrenaline.
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Q.134
Which vitamin is essential for the normal clotting of blood?
- A Vitamin A
- B Vitamin K
- C Vitamin C
- D Vitamin B1
Show answer
Correct answer: (B) Vitamin K
Vitamin K is needed by the liver to make the proteins that help blood to clot, so its deficiency leads to excessive bleeding from wounds. Green leafy vegetables are a rich source.
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Q.135
A solution is made by dissolving 20 g of common salt in 180 g of water. The concentration of the solution in terms of mass by mass percentage is
- A 11.1%
- B 20%
- C 10%
- D 9%
Show answer
Correct answer: (C) 10%
Mass of solution = 20 g + 180 g = 200 g. Mass percentage = (20/200) x 100 = 10%. Dividing by the mass of water alone (20/180) wrongly gives 11.1%.
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Q.136
Most plants take up nitrogen from the soil in the form of
- A Free nitrogen gas
- B Nitrogen dioxide gas
- C Inorganic nitrates and nitrites
- D Proteins from dead animals
Show answer
Correct answer: (C) Inorganic nitrates and nitrites
Plants cannot use free nitrogen gas directly; they absorb nitrogen from the soil mainly as inorganic nitrates or nitrites, or as organic compounds made by bacteria from atmospheric nitrogen. This nitrogen is used to make proteins.
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Q.137
Detergents are better than soaps for washing clothes in hard water because detergents
- A are made from vegetable oils
- B remove calcium and magnesium salts from the water
- C do not form insoluble scum with calcium and magnesium ions
- D are always biodegradable
Show answer
Correct answer: (C) do not form insoluble scum with calcium and magnesium ions
Soap reacts with the calcium and magnesium salts of hard water to form an insoluble precipitate called scum, which wastes soap. The charged ends of detergents do not form insoluble precipitates with these ions, so detergents work well even in hard water.
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Q.138
The inner lining of the stomach is protected from the action of hydrochloric acid by
- A Bile
- B Mucus
- C Pepsin
- D Saliva
Show answer
Correct answer: (B) Mucus
The gastric glands release mucus along with hydrochloric acid and pepsin, and under normal conditions the mucus protects the stomach lining from the acid. Bile is poured into the small intestine and saliva acts in the mouth.
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Q.139
Plaster of Paris, used for setting fractured bones, has the formula
- A CaSO4.2H2O
- B CaSO4.1/2H2O
- C CaCO3
- D CaO
Show answer
Correct answer: (B) CaSO4.1/2H2O
Plaster of Paris is calcium sulphate hemihydrate, obtained by heating gypsum (CaSO4.2H2O) to about 373 K. On mixing with water it sets back into hard gypsum.
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Q.140
When white light passes through a glass prism, which colour is deviated the most?
- A Red
- B Yellow
- C Green
- D Violet
Show answer
Correct answer: (D) Violet
Violet light has the shortest wavelength among the visible colours and bends the most in glass, while red bends the least. This difference in bending splits white light into a spectrum (dispersion).
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Q.141
In Rutherford's alpha-particle scattering experiment, most of the alpha particles passed straight through the thin gold foil. This showed that
- A Most of the space inside an atom is empty
- B The atom is a uniform sphere of positive charge
- C Electrons are present inside the nucleus
- D Gold atoms carry a large negative charge
Show answer
Correct answer: (A) Most of the space inside an atom is empty
Since most alpha particles passed undeflected, nothing stood in their path through most of the atom, so the atom is mostly empty space. Very few particles bounced back, showing that the positive charge and mass are concentrated in a tiny nucleus.
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Q.142
Adrenaline, the hormone that prepares the body to deal with emergencies ('fight or flight'), is secreted by the
- A Thyroid gland
- B Pituitary gland
- C Pancreas
- D Adrenal glands
Show answer
Correct answer: (D) Adrenal glands
Adrenaline is secreted directly into the blood by the adrenal glands, which sit on top of the kidneys. It speeds up the heartbeat and breathing and sends more blood to the muscles, preparing the body for an emergency.
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Q.143
Antibodies in the human body are produced by
- A Red blood cells
- B B-lymphocytes
- C Platelets
- D Neutrophils
Show answer
Correct answer: (B) B-lymphocytes
B-lymphocytes, a type of white blood cell, mature into plasma cells that produce antibodies against specific antigens; T-lymphocytes provide cell-mediated immunity. Red cells carry oxygen and platelets help in clotting.
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Q.144
Solder, used for welding electrical wires together, is an alloy of
- A Copper and zinc
- B Copper and tin
- C Iron and carbon
- D Lead and tin
Show answer
Correct answer: (D) Lead and tin
Solder is an alloy of lead and tin with a low melting point, which makes it suitable for joining electrical wires. Copper and zinc form brass, copper and tin form bronze, and steel is mainly iron with carbon.
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Q.145
Many desert plants keep their stomata closed during the day and take in carbon dioxide at night. The main advantage of this is that it
- A reduces the loss of water by transpiration
- B increases the absorption of sunlight
- C allows photosynthesis to take place at night
- D helps the plant to absorb more minerals
Show answer
Correct answer: (A) reduces the loss of water by transpiration
Keeping the stomata closed in the hot day greatly cuts water loss by transpiration. These plants take in carbon dioxide at night and store it as an intermediate compound, which is used for photosynthesis during the day when light is available.
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Q.146
According to Archimedes' principle, the upward force (buoyant force) on a body wholly or partially immersed in a fluid is equal to the
- A weight of the body
- B volume of the body
- C weight of the fluid displaced by the body
- D density of the fluid
Show answer
Correct answer: (C) weight of the fluid displaced by the body
Archimedes' principle: a body immersed in a fluid experiences an upward force equal to the weight of the fluid it displaces. This explains why ships float and why objects seem lighter in water.
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Q.147
A body of mass 5 kg is raised to a height of 10 m above the ground. Taking g = 10 m/s², its potential energy is
- A 50 J
- B 500 J
- C 5000 J
- D 15 J
Show answer
Correct answer: (B) 500 J
Potential energy = mgh = 5 × 10 × 10 = 500 J, taking the ground as the zero level.
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Q.148
The symbol 'K' of potassium is derived from its Latin name
- A Natrium
- B Ferrum
- C Cuprum
- D Kalium
Show answer
Correct answer: (D) Kalium
The Latin name of potassium is kalium, hence the symbol K. Natrium gives Na (sodium), ferrum gives Fe (iron) and cuprum gives Cu (copper).
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Q.149
After fertilisation in a flowering plant, the ovary develops into the
- A Seed
- B Embryo
- C Seed coat
- D Fruit
Show answer
Correct answer: (D) Fruit
After fertilisation the ovary grows and ripens into a fruit, the ovules inside it become seeds, and the zygote in each ovule develops into an embryo.
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Q.150
Which of the following statements about ionic compounds is correct?
- A They have low melting and boiling points
- B They conduct electricity in the solid state
- C They are generally soluble in kerosene and petrol
- D They conduct electricity when molten or dissolved in water
Show answer
Correct answer: (D) They conduct electricity when molten or dissolved in water
When an ionic compound is molten or dissolved in water its ions are free to move, so it conducts electricity. In the solid state the ions are held in fixed positions and cannot conduct; ionic compounds also have high melting points and are generally insoluble in kerosene and petrol.
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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.