General Science MCQs: Essential Questions for Competitive Exams in 2025
General Science is a crucial section in competitive exams like SSC, UPSC, RRB, IBPS, and state-level tests (e.g., Punjab Patwari, Haryana HSSC Clerk) in 2025. Covering Physics, Chemistry, Biology, and basic environmental science, this section tests your understanding of fundamental concepts and their real-world applications. With exams like SSC CHSL (July-August 2025) and IBPS PO (October 2025) approaching, mastering these essential Multiple Choice Questions (MCQs) can boost your score significantly. Below is a set of 20 carefully curated General Science MCQs, reflecting the latest trends and expected patterns for 2025 competitive exams, complete with answers and explanations as of March 23, 2025.
Physics
Q1. Which law explains why a person is thrown forward when a moving bus suddenly stops?
A) Newton’s First Law
B) Newton’s Second Law
C) Newton’s Third Law
D) Law of Gravitation
Answer: A) Newton’s First Law
Explanation: Newton’s First Law (Law of Inertia) states that an object in motion stays in motion unless acted upon by an external force. When the bus stops suddenly, the person’s body continues moving forward due to inertia—a common real-life scenario question.
Q2. What is the SI unit of electric current?
A) Volt
B) Ampere
C) Ohm
D) Watt
Answer: B) Ampere
Explanation: Ampere (A) is the SI unit of electric current, measuring the flow of electric charge. Volt (potential difference), Ohm (resistance), and Watt (power) are related but distinct units.
Q3. A concave mirror is used in which of the following?
A) Torch
B) Rear-view mirror
C) Solar cooker
D) Microscope
Answer: C) Solar cooker
Explanation: Concave mirrors converge light to a focal point, making them ideal for solar cookers to concentrate sunlight. Torches use convex lenses, rear-view mirrors are convex, and microscopes use a combination of lenses.
Q4. What is the primary source of energy for Earth’s climate system?
A) Geothermal energy
B) Solar energy
C) Nuclear energy
D) Tidal energy
Answer: B) Solar energy
Explanation: Solar energy drives Earth’s climate system by heating the atmosphere, oceans, and land, influencing weather patterns—a key environmental science topic.
Q5. Sound travels fastest in which medium?
A) Air
B) Water
C) Steel
D) Vacuum
Answer: C) Steel
Explanation: Sound travels fastest in solids (e.g., steel) due to closely packed particles, followed by liquids (water), then gases (air). It cannot travel in a vacuum—expect this in basic physics questions.
Chemistry
Q6. Which gas, discovered on the sun before Earth, is the second most abundant element in the universe?
A) Hydrogen
B) Helium
C) Oxygen
D) Nitrogen
Answer: B) Helium
Explanation: Helium was first detected in the sun’s spectrum during a solar eclipse in 1868 before being found on Earth. It’s the second most abundant element after hydrogen—a classic chemistry fact.
Q7. What is the chemical formula of baking soda?
A) NaCl
B) NaHCO₃
C) Na₂CO₃
D) CaCO₃
Explanation: B) NaHCO₃
Answer: Baking soda is sodium bicarbonate (NaHCO₃), used in cooking and as a mild base. NaCl is salt, Na₂CO₃ is washing soda, and CaCO₃ is limestone.
Q8. Which of the following is a noble gas?
A) Chlorine
B) Neon
C) Fluorine
D) Bromine
Answer: B) Neon
Explanation: Noble gases (Group 18) are inert due to a full valence shell. Neon is one, while chlorine, fluorine, and bromine are halogens (Group 17).
Q9. Rusting of iron is an example of:
A) Combustion
B) Oxidation
C) Reduction
D) Decomposition
Answer: B) Oxidation
Explanation: Rusting (Fe → Fe₂O₃) involves iron reacting with oxygen and moisture, losing electrons—an oxidation process frequently tested in chemistry.
Q10. What is the pH of pure water at 25°C?
A) 0
B) 7
C) 14
D) 10
Answer: B) 7
Explanation: Pure water is neutral with a pH of 7 at 25°C, where [H⁺] = [OH⁻]. Acidic solutions are below 7, and basic ones are above—a foundational concept.
Biology
Q11. Which vitamin is essential for blood clotting?
A) Vitamin A
B) Vitamin D
C) Vitamin K
D) Vitamin C
Answer: C) Vitamin K
Explanation: Vitamin K plays a key role in synthesizing clotting factors in the liver, preventing excessive bleeding—a high-frequency biology question.
Q12. What is the powerhouse of the cell?
A) Nucleus
B) Mitochondria
C) Ribosome
D) Golgi Apparatus
Answer: B) Mitochondria
Explanation: Mitochondria produce ATP (energy) through cellular respiration, earning the title “powerhouse”—a must-know cell biology fact.
Q13. Which gas do plants release during photosynthesis?
A) Carbon Dioxide
B) Oxygen
C) Nitrogen
D) Hydrogen
Answer: B) Oxygen
Explanation: Photosynthesis (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂) uses sunlight to convert carbon dioxide and water into glucose, releasing oxygen—a staple question.
Q14. Which disease is caused by the deficiency of Vitamin C?
A) Scurvy
B) Rickets
C) Beriberi
D) Night Blindness
Answer: A) Scurvy
Explanation: Scurvy results from Vitamin C deficiency, causing bleeding gums and fatigue. Rickets (Vitamin D), Beriberi (Vitamin B1), and Night Blindness (Vitamin A) are other deficiency diseases.
Q15. What is the primary source of energy for living organisms?
A) Proteins
B) Carbohydrates
C) Fats
D) Vitamins
Answer: B) Carbohydrates
Explanation: Carbohydrates (e.g., glucose) are the primary energy source via cellular respiration, while proteins and fats serve other roles—a basic nutrition concept.
Environmental Science & Miscellaneous
Q16. Which layer of the atmosphere contains the ozone layer?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer: B) Stratosphere
Explanation: The ozone layer, which absorbs UV radiation, is in the stratosphere (10-50 km above Earth)—a key environmental science topic for 2025.
Q17. What is the primary greenhouse gas emitted by human activities?
A) Methane
B) Carbon Dioxide
C) Nitrous Oxide
D) Ozone
Answer: B) Carbon Dioxide
Explanation: Carbon Dioxide (CO₂) from burning fossil fuels is the leading greenhouse gas, driving climate change—a current affairs-linked question.
Q18. Which instrument measures atmospheric pressure?
A) Thermometer
B) Barometer
C) Hygrometer
D) Anemometer
Answer: B) Barometer
Explanation: A barometer measures atmospheric pressure, critical for weather forecasting. Thermometer (temperature), Hygrometer (humidity), and Anemometer (wind speed) serve different purposes.
Q19. The process of conversion of water vapor into liquid water is called:
A) Evaporation
B) Condensation
C) Sublimation
D) Precipitation
Answer: B) Condensation
Explanation: Condensation is the phase change from vapor to liquid, forming clouds in the water cycle—an essential environmental process.
Q20. Which metal is liquid at room temperature?
A) Iron
B) Mercury
C) Aluminum
D) Copper
Answer: B) Mercury
Explanation: Mercury (Hg) is the only metal liquid at room temperature (25°C), used in thermometers—a classic chemistry question.
Why These MCQs Are Essential for 2025?
- Exam Patterns: Based on SSC CHSL, RRB NTPC, and UPSC Prelims trends, these questions cover high-weightage topics like Newton’s laws, chemical formulas, vitamin deficiencies, and environmental science.
- Current Relevance: Includes 2024-2025-relevant topics (e.g., greenhouse gases, Khelo India-type events if applicable) expected in General Awareness sections.
- Difficulty Level: Moderate, mirroring the mix of basic and application-based questions in competitive exams.
- Scoring Potential: General Science often has 10-20 questions (10-20% of total marks), making it a high-return section with straightforward answers.
How to Use This Set
- Timed Practice: Solve these 20 MCQs in 10-12 minutes (30-36 seconds per question) to match Tier 1 pacing (e.g., SSC CHSL’s 60 minutes for 100 questions).
- Error Analysis: Review explanations to avoid pitfalls, especially with negative marking (0.25 or 0.50 marks per wrong answer).
- Expand Knowledge: Pair with free resources like Testbook’s General Science PDFs or Adda247’s YouTube playlists for more practice.
- Daily Revision: Revisit 5-10 questions daily to reinforce memory and speed.
Final Note
With competition intensifying in 2025 (e.g., SSC CHSL expecting 32 lakh+ applicants for 3,000-4,000 posts), scoring 80-90% in General Science can set you apart. These essential MCQs provide a solid foundation—start practicing now, and ace your competitive exams! Need more questions or a specific topic drill? Let me know!