71st BPSC Prelims 2025 Question Paper
Explore the complete solved question paper for 71st BPSC Prelims 2025 featuring 150 solved questions with bilingual (English & Hindi) explanations, official answer key, and subject weightage breakdown.
Which one of the following terms characterizes the interaction between the herpes simplex virus and a human?
Detailed Explanation:
Parasitism is a biological interaction where the parasite benefits while the host is harmed.
The herpes simplex virus infects human cells, uses the host's cellular machinery to replicate, damages cells, and causes diseases like cold sores or genital herpes, clearly harming the host while benefiting itself — a classic example of parasitism.
Hormones are secreted by:
Detailed Explanation:
Endocrine glands (such as pituitary, thyroid, adrenal glands) secrete hormones directly into the bloodstream to regulate body functions.
Exocrine glands (like sebaceous and sweat glands) release substances through ducts, not into the blood, so they do not secrete hormones.
Full form of PHBV biodegradable polymer.
Detailed Explanation:
PHBV stands for Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), a biodegradable copolymer produced by bacterial fermentation.
The prefix "co" indicates it is a copolymer formed from two monomer units: 3-hydroxybutyrate and 3-hydroxyvalerate, making it an eco-friendly alternative to conventional plastics.
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Which compound is used for increase of octane rating?
Detailed Explanation:
Tetraethyllead (TEL) was historically the most widely used anti-knock agent added to gasoline to increase octane rating and prevent engine knocking.
Though highly effective, TEL is toxic and has been phased out globally; modern fuels use unleaded alternatives like ethanol and aromatic hydrocarbons.
Why oil is not stored in galvanized iron pot?
Detailed Explanation:
Galvanized iron is coated with zinc, which reacts with oil components to form toxic zinc compounds that make the oil unsafe for consumption.
The chemical reaction also causes rancidity, degrading the oil's taste, smell, and nutritional quality.
Moisture and acidic impurities in oil corrode the zinc coating, exposing the underlying iron to rust formation.
Since all three effects—toxicity, quality degradation, and corrosion—occur simultaneously, the correct answer is All of above.
Which compound is used in contraceptive pills?
Detailed Explanation:
Levonorgestrel is a synthetic progestin hormone widely used in oral contraceptive pills and emergency contraception; it prevents pregnancy by inhibiting ovulation, thickening cervical mucus, and altering the uterine lining.
Cholecalciferol is Vitamin D3, Venlafaxine is an antidepressant, and Cetirizine is an antihistamine for allergies—none have contraceptive properties.
Which metal compound is used for treatment of carcinoma?
Detailed Explanation:
Platinum compounds, particularly Cisplatin, are used as chemotherapeutic agents for treating carcinoma by binding to DNA in cancer cells and causing cell death.
Cisplatin is effective against testicular, ovarian, lung, and bladder cancers. Other metals like Chromium (toxic), Iron (nutrient), and Chlorine (disinfectant) are not used for cancer treatment.
Which Material is used for smart film?
Detailed Explanation:
Smart films switch transparency when voltage is applied, requiring a material that is both electrically conductive and optically transparent.
Indium tin oxide (ITO) is a transparent conducting oxide used in smart films, touchscreens, and LCDs. Calcium carbonate is a non-conductive filler in plastics. Zinc chloride is used in batteries, not films. Silica is an insulator used in glass.
Which Compound is known as night glowing pigment from below?
Detailed Explanation:
Europium-doped strontium aluminate (SrAl₂O₄:Eu²⁺,Dy³⁺) is the most efficient modern phosphorescent material used in night glowing pigments.
It absorbs light energy and slowly releases it in darkness, providing a bright afterglow lasting up to 12 hours. Other compounds listed (copper sulphide-doped zinc oxide, barium sulphate-doped copper carbonate, boron oxide-doped copper sulphate) do not exhibit significant or efficient phosphorescence for glow-in-the-dark applications.
pH value of 0.1N HCl solution is approximately:
Detailed Explanation:
HCl is a strong acid that dissociates completely: HCl → H⁺ + Cl⁻. For a monoprotic acid, 0.1N = 0.1M, so [H⁺] = 0.1 M.
pH = -log[H⁺] = -log(0.1) = -(-1) = 1.0. Options with pH 10 or 11 indicate basic solutions, not acids. pH 2.0 would require [H⁺] = 0.01 M, which is ten times more dilute.
What is the device to protect equipments from the electric shock?
Detailed Explanation:
Fuse is a safety device containing a thin wire with low melting point that melts and breaks the circuit when excess current flows, protecting equipment from electric shock, overload, and short circuits.
Generator produces electricity, Motor converts electrical to mechanical energy, and Current controller regulates current but does not automatically disconnect during faults—only the fuse provides automatic protection.
In short circuit, the value of electric current in a time circuit:
Detailed Explanation:
Short circuit occurs when a path of nearly zero resistance forms in a circuit, bypassing the normal load.
According to Ohm's Law (I = V/R), when resistance R approaches zero, the current I increases dramatically to very high values, limited only by the internal resistance of the source.
This surge can cause overheating, fires, and equipment damage, which is why fuses and circuit breakers are used for protection.
Which term in the following does not denote the electric power în electric circuit?
Detailed Explanation:
Electric power in a circuit is given by P = VI (voltage × current).
Using Ohm's law (V = IR), we can derive two more valid formulas:
• P = I²R (substituting V = IR into P = VI)
• P = V²/R (substituting I = V/R into P = VI)
✅ Option 2 (I²R): Valid power formula.
✅ Option 3 (VI): Fundamental definition of power.
✅ Option 4 (V²/R): Valid derived formula.
❌ Option 1 (IR²): Not a valid power formula. Its dimensional analysis gives (Ampere × Ohm²), which does not equal Watt (power unit).
The focal distance of a plane mirror is
Detailed Explanation:
Focal length of a mirror is f = R/2, where R is the radius of curvature.
A plane mirror has zero curvature (flat surface), so R = ∞. Therefore, f = ∞/2 = ∞. Parallel rays reflecting from a plane mirror remain parallel and never converge or diverge to form a focus point.
A pair of Oxen exerts a force of 140 newton while ploughing the field. The field ploughed is 15 meter long. The work done in ploughing the length of the field is:
Detailed Explanation:
Work done is calculated using the formula W = F × d, where F is force and d is distance.
Given Force = 140 N and Distance = 15 m, substituting values: W = 140 × 15 = 2100 Joule.
The potential energy of a freely falling body continuously decreases.
Detailed Explanation:
Potential energy (PE) decreases as height decreases during free fall, while kinetic energy (KE) increases due to increasing velocity.
Total mechanical energy (PE + KE) remains constant throughout the fall, demonstrating that the law of conservation of energy is not violated—energy transforms from one form to another but is neither created nor destroyed.
In which medium, the speed of sound is maximum?
Detailed Explanation:
Speed of sound depends on elasticity and density of the medium — highest in solids, moderate in liquids, lowest in gases.
Steel (solid) ≈ 5000–6000 m/s, Water (liquid) ≈ 1500 m/s, Air (gas) ≈ 343 m/s, Hydrogen (gas) ≈ 1284 m/s. Among given options, steel has maximum speed.
Energy consumed in a home is 250 units then the total energy in Joule will be:
Detailed Explanation:
1 unit of electrical energy = 1 kWh = 3.6 × 10⁶ joules.
250 units = 250 × 3.6 × 10⁶ J = 900 × 10⁶ J = 9 × 10⁸ J.
A truck starts from rest down a hill with a constant acceleration. It achieves 400 meters in 20 seconds. If the weight of the truck is 7 tons then what will be the force acting on it?
Detailed Explanation:
Given: Initial velocity u = 0 (starts from rest), displacement s = 400 m, time t = 20 s, mass m = 7 tons = 7000 kg.
Step 1 – Find acceleration: Using s = ut + ½at²
400 = 0 + ½ × a × (20)²
400 = 200a
a = 2 m/s²
Step 2 – Calculate force: Using F = ma
F = 7000 × 2
F = 14000 N
Answer: 14000 Newtons
We apply a force of 200 Newtons on a wooden Box and push it on the floor at constant velocity. The marginal friction force will be:
Detailed Explanation:
Constant velocity means net force = 0, so applied force equals friction force.
Applied force = 200 N, therefore kinetic friction = 200 N.
71st BPSC Prelims 2025 Questions Paper - Subject-wise Question Distribution
Current Affairs
43 Qs (28.7%)General Science
29 Qs (19.3%)Modern History
17 Qs (11.3%)Indian Polity
14 Qs (9.3%)Bihar Special
13 Qs (8.7%)Indian Geography
11 Qs (7.3%)General Mental Ability
9 Qs (6%)Ancient History
5 Qs (3.3%)World Geography
3 Qs (2%)Medieval History
2 Qs (1.3%)Indian Art & Culture
2 Qs (1.3%)Environment & Ecology
1 Qs (0.7%)World History
1 Qs (0.7%)71st BPSC Prelims 2025 Question Paper - FAQs & Analysis
Q1 How many total questions were asked in 71st BPSC Prelims 2025?
Q2 What is the subject-wise question breakdown for 71st BPSC Prelims 2025?
- Current Affairs: 43 questions (28.7%)
- General Science: 29 questions (19.3%)
- Modern History: 17 questions (11.3%)
- Indian Polity: 14 questions (9.3%)
- Bihar Special: 13 questions (8.7%)
- Indian Geography: 11 questions (7.3%)
- General Mental Ability: 9 questions (6%)
- Ancient History: 5 questions (3.3%)
- World Geography: 3 questions (2%)
- Medieval History: 2 questions (1.3%)
- Indian Art & Culture: 2 questions (1.3%)
- Environment & Ecology: 1 questions (0.7%)
- World History: 1 questions (0.7%)