Explanation

• Picosecond (ps) = 10⁻¹² seconds
• SI prefix “pico” means 10⁻¹².
• 1 picosecond = one trillionth of a second.

Additional information:

• Microsecond (μs) = 10⁻⁶ seconds
• Nanosecond (ns) = 10⁻⁹ seconds
• Millisecond (ms) = 10⁻³ seconds
• Femtosecond (fs) = 10⁻¹⁵ seconds
• Attosecond (as) = 10⁻¹⁸ seconds
• Zeptosecond (zs) = 10⁻²¹ seconds
• Yoctosecond (ys) = 10⁻²⁴ seconds

Last verified on 17-06-2026

Explanation

• The dimension of velocity is [L T⁻¹].
• Velocity is defined as displacement per unit time.
• It shows how fast and in which direction an object moves.
• It is a vector quantity.
• SI unit of velocity is m/s.

Last verified on 17-06-2026

Explanation

Ammonia reacts with carbon dioxide to form urea.

• 2NH₃ + CO₂ → NH₂COONH₄ → CO(NH₂)₂ + H₂O
• Product: Urea [CO(NH₂)₂]

Urea contains about 46% nitrogen.

• The industrial production of urea was developed by Friedrich Wöhler.

Last verified on 17-06-2026

Explanation

• The retina is the light-sensitive layer located at the back of the human eye.
• It contains special cells called rods and cones that detect light and color.
• These cells convert light into electrical signals.
• The signals are then sent to the brain through the optic nerve to produce vision.

Last verified on 11-03-2026

Explanation

• Moho discontinuity is the boundary between the Earth’s crust and mantle.
• It was discovered by seismologist Andrija Mohorovičić in 1909.
• It is identified by a sudden change in seismic wave speed.
• The crust is solid outer layer, while the mantle lies beneath it.
• Depth varies from 5–70 km depending on land or ocean area.

Last verified on 02-04-2026

Explanation

• The bodyguard of the Earth is Jupiter, which protects Earth from many comets and asteroids due to its strong gravity.
• Jupiter attracts or deflects space objects that might otherwise hit Earth.
• It is the largest planet in the solar system.
• Its strong gravitational field acts like a “shield” for inner planets.
• That is why it is often called Earth’s protector.

Last verified on 14-06-2026

Explanation

• Necrophobia is the abnormal fear of death or dead bodies.
• It is a type of specific phobia related to mortality.
• Affected individuals feel extreme anxiety when thinking about death.
• It may also include fear of corpses or funerals.
• It is a psychological anxiety disorder.

Last verified on 10-06-2026

Explanation

• The SI unit of electrical resistance is Ohm (Ω).
• It measures how much a material opposes the flow of electric current.
• Higher resistance means less current flows.
• It is defined by V = IR (Ohm’s Law).
• 1 Ohm = 1 Volt per Ampere.

Last verified on 10-06-2026

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

• The relationship between voltage, current, and resistance is described by Ohm’s Law.
• It states that current is directly proportional to voltage and inversely proportional to resistance.
• The mathematical form is V = IR.

Last verified on 09-06-2026