Science is an exciting and broad discipline that encompasses a wide range of disciplines, each looking at different aspects of the natural world. From the smallest atoms to the vastness of space, science helps us understand the world we live in. These MCQs cover fundamental concepts in Physics, Chemistry, Biology, and Earth Science. Whether you are getting ready for an exam or just want to try out your knowledge, these MCQs will test your understanding and help to strengthen key scientific principles.
MCQs of Science
1. What is the chemical formula for water?
- A) H2O
- B) CO2
- C) H2SO4
- D) NaCl
Answer: A) H2O
Water consists of two hydrogen atoms bonded to one oxygen atom, forming the chemical formula H2O.
2. Which of the following is the smallest unit of matter?
- A) Molecule
- B) Atom
- C) Cell
- D) Organism
Answer: B) Atom
An atom is the smallest unit of matter that retains the properties of an element.
3. What is the powerhouse of the cell?
- A) Nucleus
- B) Mitochondria
- C) Ribosome
- D) Endoplasmic Reticulum
Answer: B) Mitochondria
Mitochondria are responsible for producing energy in the form of ATP, making them the powerhouse of the cell.
4. What is the main source of energy for Earth?
- A) Moon
- B) Sun
- C) Earth’s core
- D) Stars
Answer: B) Sun
The Sun is the primary source of energy for Earth, driving processes like photosynthesis and weather patterns.
5. Which of the following elements is a noble gas?
- A) Nitrogen
- B) Oxygen
- C) Argon
- D) Hydrogen
Answer: C) Argon
Argon is a noble gas, known for its inert properties and found in Group 18 of the periodic table.
6. What is the process by which plants make their food?
- A) Respiration
- B) Photosynthesis
- C) Germination
- D) Transpiration
Answer: B) Photosynthesis
Plants use sunlight, carbon dioxide, and water to make their own food through the process of photosynthesis, producing glucose and oxygen.
7. What is the primary function of red blood cells in the human body?
- A) Fighting infections
- B) Carrying oxygen
- C) Digesting food
- D) Producing hormones
Answer: B) Carrying oxygen
Red blood cells are responsible for transporting oxygen from the lungs to tissues and returning carbon dioxide to the lungs.
8. Which gas do plants take in during photosynthesis?
- A) Oxygen
- B) Carbon Dioxide
- C) Nitrogen
- D) Methane
Answer: B) Carbon Dioxide
Plants absorb carbon dioxide from the air during photosynthesis and convert it into glucose and oxygen.
9. Which of the following is an example of a physical change?
- A) Burning wood
- B) Rusting of iron
- C) Freezing water
- D) Digesting food
Answer: C) Freezing water
Freezing water is a physical change as it involves a change in state, but no new substance is formed.
10. What is the boiling point of water at standard atmospheric pressure?
- A) 50°C
- B) 100°C
- C) 150°C
- D) 200°C
Answer: B) 100°C
At standard atmospheric pressure, water boils at 100°C (212°F).
11. Which of the following is an example of a chemical change?
- A) Dissolving sugar in water
- B) Boiling water
- C) Rusting of iron
- D) Melting ice
Answer: C) Rusting of iron
Rusting is a chemical change, as it involves a chemical reaction between iron and oxygen.
12. What is the main function of the human circulatory system?
- A) To digest food
- B) To circulate blood and nutrients
- C) To remove waste from the body
- D) To control body movements
Answer: B) To circulate blood and nutrients
The circulatory system transports blood, oxygen, nutrients, and hormones throughout the body, and also removes waste products.
13. What is the chemical symbol for gold?
- A) Ag
- B) Au
- C) Pb
- D) Fe
Answer: B) Au
Gold is represented by the chemical symbol Au, derived from the Latin word “aurum.”
14. Which of the following is not a state of matter?
- A) Solid
- B) Liquid
- C) Gas
- D) Plasma
Answer: D) Plasma
Plasma is a state of matter distinct from solids, liquids, and gases. It consists of highly charged particles.
15. What part of the plant conducts photosynthesis?
- A) Root
- B) Stem
- C) Leaf
- D) Flower
Answer: C) Leaf
The leaf contains chloroplasts that carry out photosynthesis, converting sunlight into energy for the plant.
16. Which planet is closest to the Sun?
- A) Earth
- B) Mars
- C) Venus
- D) Mercury
Answer: D) Mercury
Mercury is the closest planet to the Sun in our solar system.
17. Which of the following is not a function of the human skeleton?
- A) Protection of internal organs
- B) Production of blood cells
- C) Storage of minerals
- D) Digestion of food
Answer: D) Digestion of food
The skeleton is responsible for support, protection, movement, and mineral storage, but not for digestion.
18. What is the SI unit of force?
- A) Joule
- B) Newton
- C) Watt
- D) Volt
Answer: B) Newton
The SI unit of force is the Newton (N), named after Sir Isaac Newton.
19. What type of energy is stored in food?
- A) Electrical energy
- B) Chemical energy
- C) Mechanical energy
- D) Thermal energy
Answer: B) Chemical energy
Food contains chemical energy, which is released when it is metabolized by the body.
20. Which of the following is the chemical formula for methane?
- A) CH4
- B) CO2
- C) H2O
- D) O2
Answer: A) CH4
Methane has the chemical formula CH4, consisting of one carbon atom and four hydrogen atoms.
21. What is the main gas found in Earth’s atmosphere?
- A) Oxygen
- B) Carbon Dioxide
- C) Nitrogen
- D) Argon
Answer: C) Nitrogen
Nitrogen makes up about 78% of the Earth’s atmosphere.
22. What is the pH of pure water?
- A) 5
- B) 7
- C) 9
- D) 10
Answer: B) 7
Pure water has a neutral pH of 7, meaning it is neither acidic nor alkaline.
23. Which of the following is a renewable energy source?
- A) Coal
- B) Oil
- C) Solar energy
- D) Natural gas
Answer: C) Solar energy
Solar energy is renewable as it is harnessed from the Sun, which is constantly available.
24. What is the unit of electric current?
- A) Ampere
- B) Volt
- C) Ohm
- D) Watt
Answer: A) Ampere
The unit of electric current is the Ampere (A), often abbreviated as “amp.”
25. What is the process by which plants lose water through their leaves?
- A) Photosynthesis
- B) Transpiration
- C) Germination
- D) Respiration
Answer: B) Transpiration
Transpiration is the process by which plants lose water vapor from their leaves into the atmosphere.
26. Which organ in the human body is responsible for pumping blood?
- A) Brain
- B) Stomach
- C) Heart
- D) Lungs
Answer: C) Heart
The heart is responsible for pumping blood throughout the circulatory system.
27. What is the atomic number of carbon?
- A) 6
- B) 8
- C) 12
- D) 14
Answer: A) 6
The atomic number of carbon is 6, meaning it has 6 protons in its nucleus.
28. What is the main difference between plant and animal cells?
- A) Animal cells have a cell wall
- B) Plant cells have chloroplasts
- C) Animal cells have chloroplasts
- D) Plant cells lack a nucleus
Answer: B) Plant cells have chloroplasts
Chloroplasts in plant cells allow them to perform photosynthesis, which animal cells do not do.
29. Which element is most commonly used in light bulbs?
- A) Neon
- B) Krypton
- C) Tungsten
- D) Helium
Answer: C) Tungsten
Tungsten is used in light bulbs due to its high melting point and durability when heated.
30. Which of the following is a non-renewable resource?
- A) Wind
- B) Solar
- C) Coal
- D) Biomass
Answer: C) Coal
Coal is a non-renewable resource, as it takes millions of years to form and is depleted faster than it can be replenished.
31. What is the process by which a solid turns into a liquid?
- A) Condensation
- B) Freezing
- C) Melting
- D) Evaporation
Answer: C) Melting
Melting is the process by which a solid turns into a liquid when it absorbs heat.
32. What is the largest planet in our solar system?
- A) Earth
- B) Mars
- C) Jupiter
- D) Saturn
Answer: C) Jupiter
Jupiter is the largest planet in our solar system, with a diameter of about 143,000 kilometers.
33. Which of the following is the main source of food for plants?
- A) Carbon dioxide
- B) Water
- C) Sunlight
- D) Nitrogen
Answer: C) Sunlight
Plants obtain their food through photosynthesis, using sunlight, water, and carbon dioxide.
34. What type of bond is formed when two atoms share electrons?
- A) Ionic bond
- B) Covalent bond
- C) Hydrogen bond
- D) Metallic bond
Answer: B) Covalent bond
Covalent bonds are formed when atoms share electrons to achieve a full outer shell of electrons.
35. Which of the following is a characteristic of acids?
- A) Bitter taste
- B) Slippery texture
- C) Sour taste
- D) No effect on litmus paper
Answer: C) Sour taste
Acids typically have a sour taste, and they turn blue litmus paper red.
36. What is the main function of the white blood cells in the human body?
- A) Carry oxygen
- B) Help in digestion
- C) Fight infections
- D) Regulate body temperature
Answer: C) Fight infections
White blood cells are part of the immune system and help defend the body against infections and diseases.
37. What is the SI unit of temperature?
- A) Kelvin
- B) Celsius
- C) Fahrenheit
- D) Joule
Answer: A) Kelvin
The SI unit for temperature is Kelvin (K), which is used in scientific measurements.
38. Which of the following is a natural satellite of Earth?
- A) Mars
- B) The Moon
- C) Jupiter
- D) Saturn
Answer: B) The Moon
The Moon is Earth’s only natural satellite, orbiting around Earth.
39. Which force keeps the planets in orbit around the Sun?
- A) Magnetic force
- B) Gravitational force
- C) Frictional force
- D) Electromagnetic force
Answer: B) Gravitational force
The gravitational pull of the Sun keeps the planets in orbit around it, preventing them from flying off into space.
40. What is the process of converting a gas to a liquid called?
- A) Evaporation
- B) Sublimation
- C) Condensation
- D) Melting
Answer: C) Condensation
Condensation is the process where a gas cools and changes into a liquid.
41. Which of the following is an example of a compound?
- A) Oxygen
- B) Nitrogen
- C) Water
- D) Hydrogen
Answer: C) Water
Water (H2O) is a compound made from two hydrogen atoms and one oxygen atom.
42. Which of the following structures in a plant cell is responsible for storing food and water?
- A) Chloroplast
- B) Mitochondria
- C) Vacuole
- D) Nucleus
Answer: C) Vacuole
The vacuole stores water, food, and waste products in a plant cell.
43. What is the most common element in the Earth’s crust?
- A) Oxygen
- B) Iron
- C) Silicon
- D) Aluminum
Answer: A) Oxygen
Oxygen makes up about 46% of the Earth’s crust by weight, often combined with silicon to form silicate minerals.
44. Which of the following is an example of a physical change?
- A) Burning paper
- B) Boiling water
- C) Rusting iron
- D) Baking a cake
Answer: B) Boiling water
Boiling water is a physical change because the water changes from liquid to gas without changing its chemical composition.
45. What is the main function of the digestive system?
- A) To circulate blood
- B) To break down food for absorption
- C) To filter waste from the body
- D) To regulate body temperature
Answer: B) To break down food for absorption
The digestive system breaks down food into nutrients that can be absorbed by the body.
46. Which of the following is a conductor of electricity?
- A) Wood
- B) Rubber
- C) Copper
- D) Plastic
Answer: C) Copper
Copper is a good conductor of electricity and is commonly used in electrical wiring.
47. What is the chemical formula of methane?
- A) CH4
- B) C2H6
- C) CH3OH
- D) C4H10
Answer: A) CH4
Methane (CH4) is a simple organic compound consisting of one carbon atom and four hydrogen atoms.
48. What part of the brain controls basic life functions like heartbeat and breathing?
- A) Cerebrum
- B) Cerebellum
- C) Medulla Oblongata
- D) Thalamus
Answer: C) Medulla Oblongata
The medulla oblongata controls vital functions such as heart rate, breathing, and blood pressure.
49. What type of energy is stored in food?
- A) Nuclear energy
- B) Chemical energy
- C) Kinetic energy
- D) Thermal energy
Answer: B) Chemical energy
Food contains chemical energy, which the body can convert into usable energy during metabolism.
50. What is the primary component of the Earth’s atmosphere?
- A) Oxygen
- B) Carbon dioxide
- C) Nitrogen
- D) Water vapor
Answer: C) Nitrogen
Nitrogen makes up about 78% of Earth’s atmosphere, with oxygen being the second most abundant at 21%.
This concludes the 50 Science MCQs with answers, covering various scientific disciplines. Use this quiz to test your knowledge and strengthen your understanding of fundamental science concepts!
Also Read: Everyday Science MCQs: Important for Examination
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