Showing 21–30 of 208 questions
Q.21
Medium
General Science
Which element is the most abundant in the Earth's atmosphere?
A
Oxygen
B
Nitrogen
C
Argon
D
Carbon dioxide
Correct Answer:
B. Nitrogen
Explanation:
Nitrogen comprises about 78% of Earth's atmosphere, followed by oxygen at about 21%.
Q.22
Medium
General Science
What is the principal source of energy for the Earth?
A
The Moon
B
The Sun
C
Geothermal energy
D
Nuclear reactions in Earth's core
Correct Answer:
B. The Sun
Explanation:
The Sun is the primary source of energy for Earth, providing energy through radiation that drives weather, climate, and photosynthesis.
Q.23
Medium
General Science
Which of the following is an example of a physical change?
A
Rusting of iron
B
Burning of paper
C
Melting of ice
D
Digestion of food
Correct Answer:
C. Melting of ice
Explanation:
Melting of ice is a physical change as water remains H₂O but changes from solid to liquid state. Other options are chemical changes.
Q.24
Medium
General Science
In Newton's third law of motion, if object A exerts a force on object B, what does object B do?
A
Exerts an equal and opposite force on A
B
Exerts a smaller force on A
C
Exerts no force on A
D
Exerts a greater force on A
Correct Answer:
A. Exerts an equal and opposite force on A
Explanation:
Newton's third law states that for every action, there is an equal and opposite reaction. Forces always occur in pairs.
Q.25
Medium
General Science
Which of the following is the largest organ in the human body by mass?
A
Heart
B
Brain
C
Liver
D
Lung
Explanation:
The liver is the largest internal organ by mass, weighing approximately 1.5 kg in adults.
Q.26
Medium
General Science
What happens to the density of water when it freezes into ice?
A
Density increases
B
Density decreases
C
Density remains the same
D
Density becomes zero
Correct Answer:
B. Density decreases
Explanation:
Ice has lower density than water, which is why ice floats on water. Water expands when it freezes.
Q.27
Medium
General Science
Which of the following is NOT a type of simple machine?
A
Lever
B
Pulley
C
Turbine
D
Inclined plane
Correct Answer:
C. Turbine
Explanation:
A turbine is not a simple machine. The six simple machines are lever, pulley, inclined plane, wedge, screw, and wheel-axle.
Q.28
Medium
General Science
What is the primary component of natural gas?
A
Ethane
B
Propane
C
Methane
D
Butane
Correct Answer:
C. Methane
Explanation:
Methane (CH4) is the primary component of natural gas, making up about 70-90% of its composition.
Q.29
Medium
General Science
Which blood cell is responsible for carrying oxygen throughout the body?
A
White blood cells
B
Red blood cells
C
Platelets
D
Lymphocytes
Correct Answer:
B. Red blood cells
Explanation:
Red blood cells (erythrocytes) contain hemoglobin and transport oxygen from lungs to body tissues.
Q.30
Medium
General Science
What is the process by which a liquid changes into a solid?
A
Condensation
B
Freezing
C
Sublimation
D
Deposition
Correct Answer:
B. Freezing
Explanation:
Freezing is the phase change from liquid to solid, typically occurring at the freezing point of a substance.
