70th BPSC Prelims Re-exam 2025
General Science Previous Year Questions (PYQs)
Explore 28 solved 70th BPSC Prelims Re-exam 2025 General Science questions with detailed step-by-step bilingual solutions, option analysis, and answer keys.
Which of the following vitamins are water soluble?
Detailed Explanation:
Vitamins A, D, E, and K are fat-soluble vitamins that dissolve in fats and oils and are stored in the body's fatty tissues and liver.
Vitamin B-complex (B1, B2, B3, B5, B6, B7, B9, B12) and Vitamin C are water-soluble vitamins that dissolve in water, are not stored in the body, and must be replenished regularly through diet.
Since Vitamin A, D, and K listed in options 1–3 are all fat-soluble, the correct answer is "None of these".
When antigens are introduced in the body through vaccination antibodies are produced to fight off infection
Detailed Explanation:
B cells produce antibodies when antigens are introduced through vaccination.
T cells provide helper functions to activate B cells but do not produce antibodies themselves; only B cells differentiate into plasma cells that secrete antibodies.
An electron of mass M kg and charge e coulomb travels from rest through a potential difference of V volts. The final energy in joules would be
Detailed Explanation:
When a charged particle accelerates through a potential difference V, the work done by the electric field equals W = charge × voltage = eV joules.
Since the electron starts from rest, all this work converts into kinetic energy, making the final energy = eV joules. The mass M determines the final velocity but does not appear in the energy equation.
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Which of the following is responsible for production of shadow?
Detailed Explanation:
Shadows are formed because light travels in straight lines, a property called rectilinear propagation.
When an opaque object blocks light's path, it cannot bend around the obstacle, creating a dark region (shadow) behind it. Polarisation relates to wave orientation, diffraction to bending at edges, and interference to wave overlap patterns—none directly cause shadows.
One of the properties associated with X-rays is that they can be deflected by
Detailed Explanation:
X-rays are electromagnetic waves with no electric charge, so they travel unaffected by electric or magnetic fields.
Only charged particles (like electrons, protons, alpha particles) experience deflection in electric or magnetic fields; neutral electromagnetic radiation (X-rays, gamma rays, light) passes straight through.
Blood group of an individual is determined by
Detailed Explanation:
Blood group is determined by specific antigens present on the surface of red blood cells (RBCs), not by haemoglobin, WBC/RBC combination, or RBC shape.
The ABO system uses A and B antigens (Type A has A antigen, Type B has B antigen, Type AB has both, Type O has neither), while the Rh system uses the D antigen (present = Rh-positive, absent = Rh-negative).
Haemoglobin carries oxygen and does not determine blood group; WBC/RBC combination refers to cell counts, not blood typing; RBC shape is related to disorders like sickle cell anemia, not blood group determination.
Besides spreading Malaria, Anopheles mosquito's are also vectors of
Detailed Explanation:
Anopheles mosquitoes are primary vectors of malaria (caused by Plasmodium), and also transmit lymphatic filariasis (caused by Wuchereria bancrofti and Brugia species) and certain types of encephalitis (such as O'nyong-nyong fever in Africa).
Dengue is transmitted exclusively by Aedes mosquitoes (Aedes aegypti and Aedes albopictus), not Anopheles, making options 1 and 2 incorrect.
What is the unit of measure of magnetic field?
Detailed Explanation:
The SI unit of magnetic field (magnetic flux density) is Tesla (T), named after physicist Nikola Tesla.
Cobalt is a ferromagnetic metal, Ampere measures electric current, and Ohm measures electrical resistance—none measure magnetic field strength.
Light weight bullet proof helmets and jackets use which of the following fibres for their production?
Detailed Explanation:
Kevlar is a synthetic aramid fibre developed by DuPont in 1965, known for its extremely high tensile strength (5 times stronger than steel by weight) and low weight.
Its unique properties include bullet energy absorption and dispersion, flexibility, heat resistance, and fire resistance, making it the preferred material for lightweight bulletproof helmets and jackets. Terylene and Nylon lack the necessary impact resistance for ballistic protection.
Compared to a burn due to air at 100°C, the burn due to steam at 100°C is
Detailed Explanation:
Steam at 100°C contains latent heat of vaporization (540 cal/g) in addition to thermal energy, while air at 100°C has only thermal energy.
When steam condenses on skin, it releases this extra latent heat, transferring significantly more total energy than hot air, causing deeper and more severe burns.
As the diameter of objective lens of a telescope increases, the resolution of telescope
Detailed Explanation:
Resolution of a telescope is its ability to distinguish between two closely spaced objects and is inversely proportional to the angular resolution θ.
According to Rayleigh's criterion, θ = 1.22λ/D, where λ is the wavelength of light and D is the diameter of the objective lens. As D increases, θ decreases, meaning the telescope can resolve finer details — hence resolution increases.
A larger aperture also collects more light, further improving image clarity and the ability to separate closely spaced objects.
How is Hydrogen stored physically?
Detailed Explanation:
Physical storage of hydrogen means storing H₂ gas without any chemical transformation.
Compressing hydrogen gas into high-pressure tanks (350–700 bar) is the most common physical storage method – no chemical bonds are formed or broken.
Hydrides involve chemical bonding with metals/alloys (chemical storage), and water (H₂O) is a compound, not free hydrogen gas.
Turmeric powder is obtained from which part of turmeric plant?
Detailed Explanation:
Turmeric powder is obtained from the dried rhizome (underground stem) of the turmeric plant, not from root, foot, or seed.
A rhizome is botanically a modified stem that grows horizontally underground; it is distinct from true roots which absorb water and nutrients.
Options 1 ("Dried foot" - not a plant part), 2 ("Dried root" - incorrect organ), and 3 ("Seed" - turmeric rarely produces viable seeds) are all incorrect, making Option 4 ("None of the above") the correct answer.
Quinine is a common drug for malaria that is obtained from a plant. Which part of the plant yields this drug?
Detailed Explanation:
Quinine is an alkaloid drug used to treat malaria, extracted from the stem bark of the Cinchona tree.
The bark tissues contain the highest concentration of quinine and related alkaloids, which are harvested, dried, and processed for medicinal use; leaves and roots contain negligible amounts.
There is no atmosphere on the surface of the moon because
Detailed Explanation:
The Moon lacks an atmosphere because its escape velocity (2.38 km/s) is lower than the root mean square (rms) velocity of gas molecules like hydrogen and helium (1–1.5 km/s).
When the rms velocity exceeds escape velocity, gas molecules possess enough kinetic energy to overcome the Moon's weak gravitational pull and escape into space. In contrast, Earth's escape velocity (11.2 km/s) is sufficiently high to retain atmospheric gases.
Liver stores
Detailed Explanation:
The liver stores several vitamins essential for bodily functions.
Vitamin A is stored in large quantities (up to 2 years' supply) for vision, immunity, and cell growth.
Vitamin D is stored as calcifediol, regulating calcium absorption and bone health.
Vitamin B12 (cobalamin) is the only water-soluble vitamin significantly stored by the liver (up to 3–5 years' supply), supporting red blood cell formation and nerve function.
Vitamin C (ascorbic acid) is retained in smaller amounts for short-term use in collagen synthesis and immune function.
Thus, the liver stores vitamins A, B (especially B12), C, and D.
For two liquids A and B to form an ideal solution
Detailed Explanation:
An ideal solution follows Raoult's law where intermolecular forces between A–A, B–B, and A–B molecules are approximately equal.
Enthalpy of mixing (ΔHmix) = 0 because no heat is absorbed or released during mixing.
Entropy of mixing (ΔSmix) > 0 (positive) due to increased randomness, and Free energy of mixing (ΔGmix) < 0 (negative), making the process spontaneous.
The conductivity of a strong electrolyte
Detailed Explanation:
Conductivity (specific conductivity) measures the ability of a unit volume of solution to conduct electricity, depending on number of ions per unit volume.
On dilution, total ions remain constant but volume increases, so ion concentration per unit volume decreases, causing conductivity to decrease. (Note: Molar conductivity increases with dilution, but the question asks about conductivity.)
Which of the following is not an electrophile?
Detailed Explanation:
Electrophiles are electron-deficient species that accept electron pairs, typically carrying a positive charge or having an incomplete octet.
Na⁺ (sodium ion) has a stable noble-gas configuration (1s²2s²2p⁶) with no empty orbitals available to accept electrons, making it a spectator ion rather than an electrophile.
BF₃ (boron trifluoride) has an incomplete octet on boron (only 6 electrons), allowing it to act as a Lewis acid and electrophile.
H⁺ (proton) has no electrons and readily accepts electron pairs, making it a strong electrophile.
Catalyst used in hydrogenation of vegetable oil into vanaspati ghee is
Detailed Explanation:
Nickel (Ni) is the industrial catalyst used in the hydrogenation of vegetable oils to produce vanaspati ghee.
The process converts unsaturated fats (liquid oils) into saturated fats (solid ghee) by adding hydrogen in the presence of finely divided nickel at 140–225°C.
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70th BPSC Prelims Re-exam 2025 - General Science Chapter-wise Distribution
Biology
11 Qs (39.3%)Physics
8 Qs (28.6%)Chemistry
6 Qs (21.4%)Science and Technology Developments
3 Qs (10.7%)70th BPSC Prelims Re-exam 2025 - General Science Questions FAQs
Q1 How many General Science questions were asked in 70th BPSC Prelims Re-exam 2025 2024?
Q2 What is the chapter-wise question distribution for General Science in 70th BPSC Prelims Re-exam 2025 2024?
- Biology: 11 questions (39.3%)
- Physics: 8 questions (28.6%)
- Chemistry: 6 questions (21.4%)
- Science and Technology Developments: 3 questions (10.7%)