Explanation

• The speed of sound is generally maximum in solids.
• Because their particles are closely packed and elastic forces transmit vibrations rapidly.

Additional information:

• Solids: Sound generally travels fastest, e.g., Steel: 5,000–6,000 m/s
• Liquids: Sound travels slower than in most solids, e.g., Water: 1,480 m/s
• Gases: Sound travels slowest under ordinary conditions, e.g., Air at 20°C: 343 m/s

Last verified on 15-10-2026

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 Moon is Earth’s only natural satellite.
• Diameter – 3,474 km
• Distance from Earth – 384,400 km
• Orbital period – 27.3 days
• Surface gravity – 1/6th of Earth
• First human landing – Apollo 11, 1969

Last verified on 18-03-2026

Explanation

• Flowers are the reproductive structures of plants.
• It is responsible for producing seeds and facilitating sexual reproduction.
• They contain the male and female reproductive organs.
• They are essential for the production of fruits and seeds.

Last verified on 18-03-2026

Explanation

• Carbon dioxide (CO₂) — the main greenhouse gas causing global warming.

Additional information:

• Methane (CH₄) — potent, from livestock and fossil fuels.
• Nitrous oxide (N₂O) — from fertilizers and industry.
• Water vapor — natural, amplifies warming.
• Fluorinated gases — synthetic, very strong effect.

Explanation

• Navigation satellites are used to identify the location of objects on Earth.
• They provide position, navigation, and timing (PNT) services.
• These satellites help determine the exact location of people, vehicles, ships, and aircraft.
• They are widely used for navigation, mapping, and tracking.
• The most well-known navigation satellite system is GPS (Global Positioning System).

Last verified on 10-07-2026

Explanation

• Sound waves in solvents (like liquids) travel as longitudinal waves, where particles vibrate parallel to the direction of wave propagation.
• These are a type of mechanical wave, requiring a medium to travel.

Last verified on 19-03-2026

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

• Sublimation is the direct transition of a solid into a gas without passing through the liquid phase.

Additional information:

Some common sublimating substances:

• Dry ice (CO₂) – solid → gas
• Iodine crystals – solid → violet gas
• Camphor – solid → vapor
• Naphthalene (mothballs) – solid → gas
• Ammonium chloride – solid → gas

Last verified on 13-03-2026

Explanation

• Photosynthesis produces glucose and oxygen.
• Green plants use sunlight, water, and carbon dioxide.
• This process occurs in chloroplasts using chlorophyll.
• Glucose is used as food for energy and growth.
• Oxygen is released as a byproduct into the atmosphere.

Last verified on 10-03-2026