Explanation

• The part of the eye that controls the amount of light entering is the Iris.
• It adjusts the size of the pupil according to light intensity.
• In bright light, it reduces light entry; in dim light, it allows more light in.
• This process protects the retina and helps clear vision.

Last verified on 17-05-2026

Explanation

• The gravitational force keeps planets in orbit around the Sun.
• It is the force of attraction between masses.
• The Sun’s large mass pulls planets toward it.
• Planets keep moving forward, creating stable orbits.
• This balance results in circular or elliptical motion.

Last verified on 10-06-2026

Explanation

• Type: Chemical compound
• Formula: H₂O
• Elements: Hydrogen + Oxygen
• Bond: Covalent bond
• Ratio: 2 hydrogen : 1 oxygen

Last verified on 10-06-2026

Explanation

• White blood cells (WBCs) are responsible for the body’s immunity and defense system.
• They protect the body from bacteria, viruses, and infections.
• They identify and destroy harmful pathogens.
• They are also called leukocytes.

Last verified 10-06-2026

Explanation

• Chlorine has the smallest atomic radius among the given elements.
• Atomic radius decreases from left to right across a period.
• Period 3 elements: Sodium (Na), Magnesium (Mg), Aluminum (Al), Chlorine (Cl)
• Atomic radius trend: Na > Mg > Al > Cl
• Reason: Increasing nuclear charge across the period

Last verified 10-06-2026

Explanation

• At the highest point, the velocity becomes zero, but acceleration is still present.
• The object momentarily stops before coming back down.
• Acceleration due to gravity (g = 9.8 m/s² downward) remains constant.
• Only velocity changes direction, not acceleration.

Last verified on 10-06-2026

Explanation

• If resistance is doubled, the current becomes half when voltage is constant.
• This is explained by Ohm’s Law: I = V / R.
• Current is inversely proportional to resistance.
• Increasing resistance reduces the flow of current.
• So doubling resistance halves the current.

Last verified on 10-05-2026

Explanation

• Ornithology is the branch of zoology that deals with the study of birds.
• It includes bird behavior, classification, and migration patterns.
• Scientists who study birds are called ornithologists.

Last verified on 10-06-2026

Explanation

• Signed: 14 May 1955
• Headquarters: Moscow, USSR (now Russia)
• Members: USSR + 7 countries
• Type: Military defense alliance
• Purpose: Counter NATO (North Atlantic Treaty Organization)

Last verified on 10-06-2026

Explanation

Pakistan’s borders with neighbors:

• India: 2,100 km (East)
• Afghanistan: 2,611 km (West/Northwest)
• Iran: 909 km (West)

• Arabian Sea coast: 1,058 km (South)
• Total land border: 6,219 km
• Land + Sea border: 7,277 km
• Land + Sea + LOC & Working Boundary: 8,340 km