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

• Centrifugation is a separation method that uses rapid rotation to separate components according to their density.
• Cream contains fat globules that are less dense than the watery part of milk.

Additional information:

• Distillation: Separates substances based on differences in boiling points.
• Sublimation: A solid changes directly into a gas.

Last verified on 12-10-2026

Explanation

• 1 Nanometer (nm) = 10⁻⁹ m (1 × 10⁻⁹ m)

Additional information:

• 1 Kilometer (km) = 10³ m
• 1 Meter (m) = 10⁰ m
• 1 Millimeter (mm) = 10⁻³ m
• 1 Micrometer (µm) = 10⁻⁶ m

Last verified on 06-07-2026

Explanation

• Phycology is the branch of biology that studies algae.
• Algae are primarily aquatic, photosynthetic organisms found in freshwater, seawater, and moist environments.
• Phycology is also known as algology.

Additional information:

• Bacteriology: Study of bacteria
• Mycology: Study of fungi
• Virology: Study of viruses

Last verified on 12-10-2026

Explanation

• Gaps are provided between railway rails to allow for thermal expansion during hot weather.
• Metal rails expand when their temperature increases and contract when their temperature decreases.

Additional information:

• Scientific principle: Expansion of solids due to heat
• Effect of excessive heat: Rails may buckle
• Effect of cooling: Rails contract

Last verified on 12-10-2026

Explanation

• The modern periodic table arranges elements in order of increasing atomic number.
• The atomic number is the number of protons present in the nucleus of an atom.
• Elements with similar chemical properties are placed in the same group (vertical column).
• The modern periodic law was established by Henry Moseley.

Last verified on 12-10-2026

Explanation

• A neutron has no electric charge, so it is electrically neutral.

Additional information:

• A proton has a positive charge (+1).
• An electron has a negative charge (−1).

Last verified on 07-10-2026

Explanation

• The atomic number of hydrogen is 1.
• It is the first element on the periodic table. 
• Named by: Antoine Lavoisier (1783)
• Atomic mass: 1.00784 u
• Appearance: Colorless gas
• Symbol: H
• Protons: 1
• Electrons: 1

Last updated 26-07-2026 by NA

Explanation

• Velocity is a vector quantity. 
• A vector quantity has both magnitude and direction.
• Velocity, which describes the rate of change of position in a specific direction.
• It needs both a magnitude (speed) and a direction to be fully defined. 
• Vector Quantities: Velocity, momentum, torque, acceleration.
• Scalar Quantities: Work, distance, speed, mass.

Last verified on 12-10-2026

Explanation

• Main mineral in hemoglobin: Iron
• Chemical symbol: Fe
• Location: Red blood cells
• Main function: Oxygen transport throughout the body

Last verified on 12-10-2026