Practice this General Science MCQ Quiz with carefully selected general science questions and answers designed for SSC, RRB, and TNPSC exams. This quiz covers important topics from Physics, Chemistry, and Biology, helping you strengthen your basics and improve accuracy. Regular practice of general science MCQ questions is essential for scoring high in competitive exams. Attempt this general science quiz for competitive exams and boost your preparation level.
Note: Take a few minutes to read the explanations after the test. They will help you understand the answers and reinforce important topics.
General Science MCQ Quiz 1 – Detailed Explanation
This General Science MCQ Quiz concept booster covers important topics from Physics, Chemistry, and Biology that are frequently asked in SSC, RRB, and TNPSC exams. Understanding these general science concepts will help you answer general science MCQ questions accurately and improve your overall score. Use this section as a quick revision guide before attempting more general science quizzes for competitive exams.
Q1. Which gas is most abundant in the Earth’s atmosphere?
Answer: Nitrogen
Explanation
Nitrogen is the most abundant gas in Earth’s atmosphere, making up about 78% of the atmosphere by volume. Oxygen is the second most abundant gas, making up about 21%. The remaining small percentage consists mainly of argon, carbon dioxide, water vapour and other gases.
Nitrogen is essential for life because it is a major component of proteins and nucleic acids such as DNA. However, most plants cannot directly use atmospheric nitrogen in the form of nitrogen gas. It must be converted into usable nitrogen compounds through processes such as nitrogen fixation.
Additional Information
- Nitrogen gas occurs naturally in the atmosphere mainly as N₂.
- Nitrogen is an essential nutrient required for plant growth.
- Nitrogen-fixing bacteria help convert atmospheric nitrogen into forms that plants can use.
- Animals obtain nitrogen mainly through the food they consume.
- The movement of nitrogen between the atmosphere, soil, plants and animals is known as the nitrogen cycle.
Q2. What is the chemical formula of water?
Answer: H₂O
Explanation
Water is a chemical compound made up of hydrogen and oxygen. Its chemical formula H₂O shows that each water molecule contains two hydrogen atoms chemically bonded with one oxygen atom. Water is essential for the survival of plants, animals and other living organisms.
Water is involved in many important biological processes. It helps transport dissolved substances, supports chemical reactions in living cells and plays an important role in regulating temperature. It is also an important natural resource for agriculture, domestic use and industry.
Additional Information
- Water can naturally exist as a solid, liquid and gas.
- Ice is the solid form of water, while water vapour is its gaseous form.
- Evaporation changes liquid water into water vapour.
- Condensation changes water vapour into liquid water.
- Water continuously moves through the atmosphere, land and water bodies as part of the water cycle.
Q3. Which part of the plant conducts photosynthesis?
Answer: Leaf
Explanation
The leaf is the main part of a green plant where photosynthesis takes place. It contains chlorophyll, a green pigment that absorbs light energy from the Sun. During photosynthesis, the plant uses carbon dioxide and water in the presence of light energy to produce glucose, which is used as food. Oxygen is released as a by-product.
The structure of a leaf is well suited for photosynthesis. Its broad surface helps capture sunlight, while tiny openings called stomata allow the exchange of gases. Carbon dioxide enters through the stomata, and oxygen produced during photosynthesis can leave through these openings.
Additional Information
- Photosynthesis mainly takes place in chloroplasts present in green plant cells.
- Chloroplasts contain chlorophyll and are the organelles responsible for photosynthesis.
- Glucose produced during photosynthesis can be converted into starch and stored in the plant.
- The roots mainly absorb water and minerals from the soil.
- The stem helps transport water and minerals to the leaves and distributes food produced by the plant.
Q4. The unit of electric current is:
Answer: Ampere
Explanation
Electric current refers to the flow of electric charge through a conductor. The SI unit used to measure electric current is the ampere, represented by the symbol A. The amount of current in a circuit depends on the movement of electric charges through the conducting path.
The ampere is one of the seven SI base units. An instrument called an ammeter is used to measure electric current in an electrical circuit. In a simple circuit, current flows through the conducting path when the circuit is complete and there is a potential difference.
Additional Information
- Electric current is represented by the symbol I.
- The SI unit of electric current is ampere (A).
- An ammeter is used to measure electric current.
- Current is measured by connecting an ammeter in series with the circuit.
- Volt is the unit of potential difference.
- Ohm is the unit of electrical resistance.
- Watt is the unit of power.
Q5. Which planet is known as the Red Planet?
Answer: Mars
Explanation
Mars is known as the Red Planet because its surface contains iron-bearing minerals that have reacted with oxygen and formed iron oxides. These iron oxides, often described as rust-like compounds, are present in the dust and rocks on the Martian surface and give the planet its reddish appearance.
Mars is the fourth planet from the Sun and is a terrestrial planet with a rocky surface. It has a thin atmosphere composed mainly of carbon dioxide. Mars also has surface features such as mountains, valleys, volcanoes and impact craters, showing evidence of a geologically diverse past.
Additional Information
- Mars is the fourth planet from the Sun.
- Mars is one of the four rocky planets in the Solar System.
- It has two natural satellites called Phobos and Deimos.
- The atmosphere of Mars consists mainly of carbon dioxide.
- A Martian day, called a sol, is slightly longer than an Earth day.
- Mars takes about 687 Earth days to complete one revolution around the Sun.
Q6. Which vitamin helps in blood clotting?
Answer: Vitamin K
Explanation
Vitamin K plays an essential role in normal blood clotting. It is needed by the liver to produce several proteins called clotting factors, which help the blood form a stable clot when a blood vessel is injured. Without sufficient vitamin K, the blood may take longer to clot, increasing the risk of excessive bleeding.
Vitamin K is also involved in maintaining normal bone health. It is obtained from foods such as green leafy vegetables, and some vitamin K is also produced by bacteria present in the intestine.
Additional Information
- Vitamin K is a fat-soluble vitamin.
- Important forms include vitamin K₁ (phylloquinone) and vitamin K₂ (menaquinones).
- Green leafy vegetables such as spinach, kale and cabbage are good sources of vitamin K.
- Vitamin K is required for the production of several blood-clotting factors in the liver.
- Severe vitamin K deficiency can lead to prolonged bleeding.
- Newborn babies may have low vitamin K stores, which is why vitamin K supplementation is commonly given after birth.
Q7. What is the hardest natural substance?
Answer: Diamond
Explanation
Diamond is considered the hardest naturally occurring mineral. Its exceptional hardness is due to the arrangement of carbon atoms in a strong three-dimensional crystal structure. Each carbon atom is firmly bonded to four other carbon atoms, forming a rigid network that makes diamond highly resistant to scratching.
The hardness of minerals is commonly compared using the Mohs scale of mineral hardness. Diamond has a value of 10 on this scale, which is the highest value. This means that diamond can scratch all other minerals on the Mohs scale.
Additional Information
- Diamond is made entirely of carbon.
- Diamond has a hardness of 10 on the Mohs scale.
- Graphite is also made of carbon but is much softer because its carbon atoms are arranged differently.
- Diamond forms deep inside the Earth under very high pressure and temperature.
- Diamonds are used not only in jewellery but also in cutting, drilling and grinding tools.
- Hardness refers to resistance to scratching and is different from toughness, which refers to resistance to breaking or chipping.
Q8. Sound travels fastest in:
Answer: Steel
Explanation
Sound is a mechanical wave that travels through a medium by causing particles in the medium to vibrate. It cannot travel through a vacuum because a vacuum has no particles to transmit these vibrations.
The speed of sound generally depends on the properties of the medium. In solids, particles are closely packed and the material is generally more rigid, allowing vibrations to be transmitted more rapidly. Therefore, sound travels faster through solids than through liquids and gases. Among the given options, steel is a solid, so sound travels fastest through it.
Additional Information
- Sound needs a material medium such as a solid, liquid or gas to travel.
- Sound cannot travel through a vacuum.
- In general, the speed of sound is greatest in solids, followed by liquids and then gases.
- At about 20°C, sound travels through air at approximately 343 m/s.
- Sound travels through water much faster than through air.
- The speed of sound in steel is several kilometres per second and depends on the type and properties of the steel.
Q9. Which organ purifies blood in the human body?
Answer: Kidney
Explanation
The kidneys are important organs of the excretory system that filter the blood and remove metabolic wastes and excess substances from the body. They remove wastes such as urea, along with excess water and salts, and form urine. This helps maintain the proper chemical balance of the blood and the body’s internal environment.
Humans normally have two kidneys, located on either side of the vertebral column in the abdominal region. Each kidney contains millions of tiny filtering units called nephrons. Blood is filtered through these nephrons, while useful substances such as appropriate amounts of water, glucose and salts are reabsorbed back into the blood.
Additional Information
- The functional unit of the kidney is the nephron.
- Urea is a major nitrogenous waste removed by the kidneys.
- Urine is formed in the kidneys and carried to the urinary bladder through the ureters.
- The urinary bladder temporarily stores urine before it is eliminated through the urethra.
- Kidneys also help maintain water and salt balance in the body.
- The liver also helps process and detoxify various substances, but the kidneys are the organs primarily responsible for filtering blood and removing wastes to form urine.
Q10. What is the boiling point of water at sea level?
Answer: 100°C
Explanation
At sea level, pure water boils at 100°C when the surrounding pressure is approximately one standard atmosphere (1 atm). Boiling occurs when the vapour pressure of the water becomes equal to the pressure acting on its surface. At this point, water changes from its liquid state into water vapour throughout the liquid.
The boiling point of water is not the same under all conditions. It changes with atmospheric pressure. At higher altitudes, atmospheric pressure is lower, so water boils at a temperature below 100°C. At higher pressures, the boiling point increases.
Additional Information
- The standard boiling point of water is 100°C at 1 atm pressure.
- Water freezes at 0°C at standard atmospheric pressure.
- Boiling is a change of state from liquid to gas.
- Atmospheric pressure decreases as altitude increases.
- At high altitudes, water boils at a lower temperature than 100°C.
- A pressure cooker increases the pressure inside the vessel, allowing water to reach a temperature above 100°C before boiling.
Q11. Which metal is liquid at room temperature?
Answer: Mercury
Explanation
Mercury is a metal that remains in the liquid state at ordinary room temperature. It has a melting point of about −38.8°C, so it remains liquid under normal environmental conditions. Mercury has a silvery appearance and is a good conductor of electricity.
Its unusual physical state made mercury useful in traditional thermometers, barometers and some scientific instruments. However, mercury and many of its compounds are toxic, so their use is now restricted in many applications.
Additional Information
- Mercury is represented by the chemical symbol Hg.
- Its atomic number is 80.
- Mercury is a member of the transition metals.
- Mercury has a very high density compared with many other common metals.
- Bromine is another element that is liquid at room temperature, but it is a non-metal.
- Gallium can melt in the hand because its melting point is about 29.8°C, but it is normally solid at typical room temperature.
Q12. Which force pulls objects toward Earth?
Answer: Gravity
Explanation
Gravity is the attractive force that acts between objects that have mass. On Earth, gravity pulls objects toward the centre of the Earth. This is why objects released from a height fall toward the ground instead of moving away from the Earth.
Earth’s gravitational force also keeps the Moon in orbit around Earth and keeps artificial satellites in their orbits. The gravitational attraction between the Earth and the Sun helps keep Earth in its orbit around the Sun.
Additional Information
- Gravity acts on all objects that have mass.
- The acceleration due to gravity near Earth’s surface is approximately 9.8 m/s².
- The weight of an object is the gravitational force acting on it.
- Mass remains constant, while weight can change depending on the strength of gravity.
- Gravity is responsible for keeping planets, moons and artificial satellites in their respective orbits.
- The strength of gravity decreases as the distance between objects increases.
Q13. Which gas do plants absorb during photosynthesis?
Answer: Carbon Dioxide
Explanation
Plants absorb carbon dioxide from the atmosphere during photosynthesis. The gas enters the leaves mainly through tiny openings called stomata. Inside the leaf, carbon dioxide is used along with water and light energy to produce glucose, which serves as food for the plant. Oxygen is released as a by-product of this process.
Carbon dioxide therefore provides the carbon needed to build glucose and other organic substances in the plant. The process of photosynthesis is one of the main ways carbon dioxide is removed from the atmosphere and oxygen is released into it.
Additional Information
- Carbon dioxide enters the leaf mainly through stomata.
- Water required for photosynthesis is absorbed from the soil by the roots.
- Chlorophyll captures light energy needed for photosynthesis.
- Glucose produced during photosynthesis can be converted into starch for storage.
- Oxygen released during photosynthesis enters the atmosphere through the leaves.
- Photosynthesis helps maintain the balance of carbon dioxide and oxygen in the atmosphere.
Q14. The human heart has how many chambers?
Answer: 4
Explanation
The human heart has four chambers: two upper chambers called the right atrium and left atrium, and two lower chambers called the right ventricle and left ventricle. These chambers work together to receive blood and pump it to the lungs and the rest of the body.
The right side of the heart mainly handles deoxygenated blood returning from the body and sends it to the lungs for oxygenation. The left side receives oxygen-rich blood from the lungs and pumps it to different parts of the body through the systemic circulation.
Additional Information
- The upper chambers of the heart are called atria, while the lower chambers are called ventricles.
- The right atrium receives deoxygenated blood from the superior and inferior vena cava.
- The right ventricle pumps deoxygenated blood to the lungs through the pulmonary artery.
- The left atrium receives oxygenated blood from the lungs through the pulmonary veins.
- The left ventricle pumps oxygenated blood to the body through the aorta.
- Valves in the heart help prevent the backward flow of blood.
Q15. Which planet is the largest in the solar system?
Answer: Jupiter
Explanation
Jupiter is the largest planet in the Solar System. It is a gas giant composed mainly of hydrogen and helium and has no solid surface like Earth. Its enormous size and mass give it a strong gravitational influence on other objects in the Solar System.
Jupiter rotates very rapidly, completing one rotation in about 10 hours. Its atmosphere contains prominent bands of clouds and large storms, including the Great Red Spot, a long-lasting storm system.
Additional Information
- Jupiter is the fifth planet from the Sun.
- It is the largest planet in the Solar System in both diameter and mass.
- Jupiter has a large number of known moons, including the four major Galilean moons: Io, Europa, Ganymede and Callisto.
- Ganymede, one of Jupiter’s moons, is the largest moon in the Solar System.
- Jupiter has a faint ring system.
- Its Great Red Spot is a huge atmospheric storm that has been observed for centuries.
Q16. The SI unit of work is:
Answer: Joule
Explanation
In physics, work is said to be done when a force causes an object to move through a distance in the direction of the applied force. The SI unit of work is the joule, represented by the symbol J.
One joule of work is done when a force of one newton moves an object through a distance of one metre in the direction of the force. Therefore, the relationship between work, force and displacement can be expressed as W = F × s when the force and displacement are in the same direction.
Additional Information
- The SI unit of work is joule (J).
- The joule is named after the English physicist James Prescott Joule.
- Newton (N) is the SI unit of force.
- Watt (W) is the SI unit of power.
- Pascal (Pa) is the SI unit of pressure.
- Work can be positive, negative or zero depending on the direction of force and displacement.
Q17. Which blood group is universal donor?
Answer: O Negative
Explanation
O negative is commonly referred to as the universal donor blood type for red blood cell transfusions. Red blood cells of the O negative type do not have A, B, or RhD antigens on their surface. Therefore, they are less likely to be attacked by antibodies in the recipient’s blood during an emergency red-cell transfusion.
However, blood transfusion compatibility is more specific than simply matching the ABO blood group. In medical practice, blood is carefully typed and cross-matched whenever possible to reduce the risk of transfusion reactions.
Additional Information
- The ABO blood group system has four main types: A, B, AB and O.
- The Rh system classifies blood as positive or negative based mainly on the presence or absence of the RhD antigen.
- O negative is particularly important in emergency situations when the recipient’s blood type is not yet known.
- AB positive is commonly described as the universal recipient for red blood cells.
- The universal-donor concept applies primarily to red blood cell transfusion; plasma compatibility follows different rules.
- Even when O negative blood is used, proper blood-bank testing and matching remain important.
Q18. What is the main source of energy for Earth?
Answer: Sun
Explanation
The Sun is the primary source of energy for Earth. It continuously releases energy in the form of electromagnetic radiation, including visible light and infrared radiation. This energy drives many natural processes on Earth and provides the light and heat necessary for life.
Green plants capture a portion of the Sun’s light energy through photosynthesis and convert it into chemical energy stored in food. This stored energy then passes through food chains when animals consume plants or other organisms. Solar energy also drives the water cycle and contributes to winds and weather patterns.
Additional Information
- Sunlight provides the energy needed for photosynthesis in green plants.
- Solar energy drives the water cycle through processes such as evaporation.
- Uneven heating of Earth’s surface by the Sun contributes to the formation of winds.
- Coal, petroleum and natural gas ultimately contain energy that originally came from ancient sunlight captured by organisms.
- Solar energy can be converted directly into electricity using solar cells or photovoltaic panels.
- The Sun is a star at the centre of our Solar System.
Q19. Which instrument measures atmospheric pressure?
Answer: Barometer
Explanation
A barometer is an instrument used to measure atmospheric pressure, which is the pressure exerted by the weight of the air surrounding Earth. Atmospheric pressure is an important factor in understanding weather conditions because changes in air pressure are often associated with changes in weather.
Traditional mercury barometers measure pressure by observing the height of a column of mercury. Modern instruments may use aneroid mechanisms or electronic sensors instead of mercury.
Additional Information
- Atmospheric pressure is commonly measured in pascals (Pa), hectopascals (hPa) or millibars (mb).
- Standard atmospheric pressure at sea level is approximately 1013 hPa.
- A mercury barometer uses the height of a mercury column to indicate pressure.
- An aneroid barometer measures pressure without using a liquid.
- A rapid fall in atmospheric pressure can be associated with approaching unsettled weather.
- A thermometer measures temperature, while a hygrometer measures humidity.
Q20. Which part of the cell contains genetic material?
Answer: Nucleus
Explanation
The nucleus is a membrane-bound organelle found in most eukaryotic cells and contains the cell’s main genetic material in the form of DNA. DNA carries the genetic instructions that control the growth, development, functioning and reproduction of the organism.
Inside the nucleus, DNA is organized into structures called chromosomes. Genes are specific sections of DNA that contain information for particular inherited characteristics and for producing functional molecules such as proteins. The nucleus also helps regulate many activities of the cell by controlling the expression of genetic information.
Additional Information
- DNA stands for deoxyribonucleic acid.
- Chromosomes are structures made mainly of DNA and proteins.
- Genes are functional units of heredity located on DNA.
- The nucleus is surrounded by a nuclear envelope containing nuclear pores.
- The nucleolus, present inside the nucleus, is involved in the formation of ribosomes.
- Prokaryotic cells such as bacteria do not have a membrane-bound nucleus; their DNA is located in a region called the nucleoid.
Further Reading:
For detailed science concepts and clear explanations, refer to the official NCERT Science textbooks available on the NCERT website:
👉 NCERT Official Website – 10th Science Textbooks
