Explanation

• The ozone layer acts as Earth’s natural sunscreen, protecting life from the sun’s harmful ultraviolet (UV) radiation.
• UV radiation can cause skin cancer, eye damage, and harm to plants and animals.

Additional information:

• Chemical Formula: O₃ (three oxygen atoms)
• Layer Location: Stratosphere, 15–40 km above Earth
• Function: Absorbs UV-B and UV-C rays from the Sun
• Depletion Causes: Air pollution, CFCs, industrial chemicals
• Protection Measures: Reduce CFC use, ozone-friendly products

Last verified on 09-03-2026

Explanation

• A covalent bond is formed between two non-metal atoms. 
• Examples: Molecule formation like H₂O and CO₂.
• Properties: Generally results in lower melting/boiling points compared to ionic compounds.
• These atoms achieve stability by sharing one or more pairs of valence electrons to fill their outer shells

Last updated on 09-03-2026

Explanation

Elements or compounds that combine in a chemical reaction are called reactants.

Explanation

• Petroleum, Coal, and Natural gas are all fossil fuels. 
• They are non-renewable energy sources 
• Major contributors to global energy production.
• Coal: A solid fossil fuel primarily derived from ancient swamp plants.
• Petroleum (Oil): from the remains of marine microorganisms like plankton.
• Natural gas: Composed of methane, often found in underground deposits alongside petroleum or coal

Last updated on 06-March-2026

Explanation

• Sublimation is the process in which a solid directly changes into a gas without passing through a liquid phase.
• This endothermic phase transition
• Occurs when a substance absorbs enough energy to overcome intermolecular forces.
• Deposition: Gas to Solid (the reverse process).
• Examples: Dry ice, iodine, frost/snow.

Explanation

• Non-luminous objects do not produce their own light; they are visible because they reflect light from other sources.
• The Moon is non-luminous; it reflects sunlight.
• Luminous objects like the Sun, stars, and fireflies produce their own light.

Last verified on 06-03-2026

Explanation

• A translucent object allows some light to travel through it, but scatters or absorbs some of the light, making it semi-transparent.
• Examples: Frosted glass, wax paper, and tissue paper.

Additional information:

• Transparent: Allows all light to pass through, providing a clear view. 
• Opaque: Does not allow any light to pass through.

Last verified on 06-03-2026

Explanation

Chromosomes are made up of:

• Nucleic acid (DNA or RNA)
• Proteins (histones and non-histone proteins)

A chromosome is made up of proteins and DNA organized into genes.

Each cell normally contains 23 pairs of chromosomes.

Explanation

Explanation

• Stomata are tiny pores on leaf surfaces that control gas exchange and water loss.
• Their opening and closing is regulated by certain nutrients.

• Adequate potassium improves drought tolerance and water-use efficiency in crops.
• Crops like wheat, rice, and sugarcane respond strongly to potassium fertilization.

Last verified on 01-02-2026