These essential MCQ questions are selected from the most important topics in the NSO (National Science Olympiad) examinations 2026 conducted by SOF (Science Olympiad Foundation). Sections include Physics, Chemistry, Biology, Mental Ability and Achievers Section for students of Class 1 to Class 12. For truely unlimited daily MCQ practice, visit Vooo AI Education.
🔬 Science Olympiad NSO
1Which organelle is called the powerhouse of the cell?
Answer: C — Mitochondria
Mitochondria are called the powerhouse of the cell because they produce ATP (adenosine triphosphate) — the energy currency of the cell — through the process of cellular respiration. Mitochondria have their own DNA and are believed to have originated from ancient bacteria (endosymbiotic theory).
Mitochondria are called the powerhouse of the cell because they produce ATP (adenosine triphosphate) — the energy currency of the cell — through the process of cellular respiration. Mitochondria have their own DNA and are believed to have originated from ancient bacteria (endosymbiotic theory).
2The unit of force in the SI system is:
Answer: C — Newton
The SI unit of force is the Newton (N), named after Sir Isaac Newton. 1 Newton = 1 kg·m/s² — the force required to accelerate a 1 kg mass at 1 m/s². Newton's Second Law: F = ma. The dyne is the CGS unit of force (1 N = 100,000 dynes).
The SI unit of force is the Newton (N), named after Sir Isaac Newton. 1 Newton = 1 kg·m/s² — the force required to accelerate a 1 kg mass at 1 m/s². Newton's Second Law: F = ma. The dyne is the CGS unit of force (1 N = 100,000 dynes).
3Which of the following is a noble gas?
Answer: D — Argon
Argon (Ar) is a noble gas in Group 18 of the periodic table. Noble gases (He, Ne, Ar, Kr, Xe, Rn) have complete outer electron shells making them chemically inert and unreactive. Argon makes up about 0.93% of Earth's atmosphere and is used in light bulbs and welding.
Argon (Ar) is a noble gas in Group 18 of the periodic table. Noble gases (He, Ne, Ar, Kr, Xe, Rn) have complete outer electron shells making them chemically inert and unreactive. Argon makes up about 0.93% of Earth's atmosphere and is used in light bulbs and welding.
4The process of conversion of sugar into alcohol by yeast is:
Answer: C — Fermentation
Fermentation is the anaerobic process by which yeast converts glucose (sugar) into ethanol (alcohol) and carbon dioxide. Equation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. This process is used in making bread, beer, wine and yogurt. Louis Pasteur established the microbial basis of fermentation.
Fermentation is the anaerobic process by which yeast converts glucose (sugar) into ethanol (alcohol) and carbon dioxide. Equation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. This process is used in making bread, beer, wine and yogurt. Louis Pasteur established the microbial basis of fermentation.
5Which planet has rings around it?
Answer: D — Saturn
Saturn is most famous for its spectacular ring system, but Jupiter, Uranus and Neptune also have rings. Saturn's rings are made of ice particles, rocky debris and dust, extending up to 282,000 km from the planet. The rings are named alphabetically (A, B, C, D, E, F, G) in order of their discovery.
Saturn is most famous for its spectacular ring system, but Jupiter, Uranus and Neptune also have rings. Saturn's rings are made of ice particles, rocky debris and dust, extending up to 282,000 km from the planet. The rings are named alphabetically (A, B, C, D, E, F, G) in order of their discovery.
6The pH of pure water is:
Answer: B — 7
Pure water has a pH of 7 and is neutral — neither acidic nor basic. The pH scale ranges from 0 to 14. pH < 7 is acidic, pH > 7 is basic/alkaline. pH is the negative logarithm of hydrogen ion concentration: pH = -log[H⁺]. At 25°C, pure water has equal H⁺ and OH⁻ ion concentrations.
Pure water has a pH of 7 and is neutral — neither acidic nor basic. The pH scale ranges from 0 to 14. pH < 7 is acidic, pH > 7 is basic/alkaline. pH is the negative logarithm of hydrogen ion concentration: pH = -log[H⁺]. At 25°C, pure water has equal H⁺ and OH⁻ ion concentrations.
7Which gas is produced during the rusting of iron?
Answer: C — Oxygen is consumed
Rusting of iron is an oxidation reaction where iron reacts with oxygen in the presence of water/moisture to form iron oxide (rust): 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃. Oxygen is consumed — not produced — in this reaction. Rusting is prevented by painting, galvanising or using stainless steel.
Rusting of iron is an oxidation reaction where iron reacts with oxygen in the presence of water/moisture to form iron oxide (rust): 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃. Oxygen is consumed — not produced — in this reaction. Rusting is prevented by painting, galvanising or using stainless steel.
8The human eye focuses light on which part?
Answer: C — Retina
The retina is the light-sensitive layer at the back of the eye where images are focused. It contains photoreceptors — rods (detect light/dark) and cones (detect colour). The image formed on the retina is inverted; the brain corrects this. The optic nerve transmits signals from the retina to the brain.
The retina is the light-sensitive layer at the back of the eye where images are focused. It contains photoreceptors — rods (detect light/dark) and cones (detect colour). The image formed on the retina is inverted; the brain corrects this. The optic nerve transmits signals from the retina to the brain.
9Newton's Third Law states that:
Answer: B — Every action has an equal and opposite reaction
Newton's Third Law of Motion states: "For every action, there is an equal and opposite reaction." The two forces act on different objects. Examples: rocket propulsion (exhaust gases push back, rocket moves forward), swimming (pushing water back, body moves forward), gun recoil.
Newton's Third Law of Motion states: "For every action, there is an equal and opposite reaction." The two forces act on different objects. Examples: rocket propulsion (exhaust gases push back, rocket moves forward), swimming (pushing water back, body moves forward), gun recoil.
10Which part of the brain controls balance and coordination?
Answer: C — Cerebellum
The cerebellum (Little Brain) at the back of the brain controls balance, coordination and fine motor movements. It receives information from the sensory systems, spinal cord and other brain parts to regulate movement. Damage to the cerebellum causes unsteady gait and loss of coordination (ataxia).
The cerebellum (Little Brain) at the back of the brain controls balance, coordination and fine motor movements. It receives information from the sensory systems, spinal cord and other brain parts to regulate movement. Damage to the cerebellum causes unsteady gait and loss of coordination (ataxia).
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