Explanation

• Smog is a combination of smoke and fog.
• The word smog is formed from smoke + fog.
• It is a type of air pollution that reduces visibility and can harm human health.
• Smog is commonly associated with vehicle emissions and industrial pollutants.

Last verified on 06-10-2026

Explanation

• The troposphere is the lowest layer of the atmosphere.
• Most weather phenomena occur in this layer.
• Clouds, rain, storms, and winds mainly occur here.
• It extends roughly 8–15 km above Earth’s surface.

• Mesosphere: About 50–85 km; most meteors burn up here.
• Ionosphere: Region with many charged particles; important for radio communication and auroras.
• Stratosphere: About 12–50 km; contains the ozone layer.

Explanation

• Nicolaus Copernicus proposed the heliocentric model.
• Heliocentric means the Sun is at the center.
• Earth and other planets revolve around the Sun.
• Proposed in the 16th century.
• Ptolemy supported the geocentric model (Earth-centered).

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

• Cumulonimbus clouds are tall, dense clouds associated with thunderstorms.
• They can produce hail, heavy rain, lightning, and strong winds.
• Hail forms when strong updrafts inside these storm clouds carry water droplets upward, where they freeze.

Last verified on 09-09-2026

Explanation

• Phosphorus is not among the top 10 most abundant elements in the Earth's crust.
• Most abundant element in Earth crust is Oxygen.
• Oxygen in the crust is (46. 1%).
• The chemical formula of oxygen (dioxygen) is O2.

List of 10 Most Abundant Elements in the Earth's Crust:

Last verified on 01-09-2026

Explanation

• The main reaction occurring in the Sun's core is nuclear fusion.
• In fusion, hydrogen nuclei combine to form helium, releasing a huge amount of energy.
• This energy is responsible for the Sun's light and heat.
• The Sun's primary fusion process is the proton–proton chain reaction.

Last verified on 01-09-2026

Explanation

• A series of steps is called a staircase, stairway, or a flight of stairs

Additional information:

• Tread: The flat, horizontal top surface where you place your foot.
• Riser: The vertical part that forms the gap between one step and the next.
• Nosing: The front, rounded edge of the tread that sticks out over the riser

Last updated 14 August 2026 by NA

Explanation

• Ozone (O₃) is mainly found in the Stratosphere, called the ozone layer.
• It absorbs harmful ultraviolet (UV) radiation from the sun, protecting life on Earth.
• Located roughly 15–35 km above the Earth’s surface.

Last verified on 17-01-2026

Explanation

• A rainbow is produced due to the dispersion of sunlight by water droplets in the atmosphere.
• White sunlight splits into seven colours when it passes through raindrops.
• The formation of a rainbow involves refraction, dispersion, and internal reflection.
• Dispersion is the phenomenon responsible for separating white light into its constituent colours.
• Rainbows are usually seen opposite the Sun after rainfall.

Last verified on 26-07-2026