Explanation

• Lead pencil is made up of graphite.
• Graphite is a form (allotrope) of carbon.
• It is soft and leaves marks on paper easily.
• It is used in pencils because of its slippery layered structure.
• Despite the name “lead pencil,” it contains no real lead.
• Graphite was named by Abraham Gottlob Werner in 1789.

Last verified on 21-06-2026

Explanation

• Diamond is a naturally occurring allotropic form of carbon.
• Allotropy means a single element can exist in more than one form with different structures and properties.
• It is extremely hard.
• It has a high melting point.
• It is widely used in jewelry and cutting tools.

Additional information:

• Graphite – soft, good conductor
• Fullerenes (C60) – spherical molecules
• Carbon nanotubes – tubular, high strength
• Amorphous carbon – coal, soot
• Lonsdaleite – hexagonal diamond

Last verified on 17-01-2026

Explanation

• Alcohol is soluble in water (can dissolve in water).
• It forms hydrogen bonds with water molecules.
• Common example: ethanol mixes completely with water.

Last verified on 20-06-2026

Explanation

• Discoverer: Victor Hess
• Year: 1912
• Method: High-altitude balloon experiments
• Nobel Prize: 1936 (Physics)
• Field: Astrophysics / Space radiation

Last verified on 20-06-2026

Explanation

• Between the melting point and boiling point, a substance exists in the liquid state.
• At melting point, solid changes into liquid.
• At boiling point, liquid changes into gas.
• So in between these two points, the substance remains stable as a liquid.

Last verified on 20-06-2026

Explanation

• Total standard zones: 24
• Earth rotation time: 24 hours
• Longitude per zone: 15 degrees
• Starting point: Greenwich (0°)
• It is used worldwide for time coordination.

Last verified on 14-06-2026

Explanation

• Vascular tissue is present in both angiosperms and gymnosperms.
• It includes xylem and phloem.
• It helps in transport of water and food.
• Both plant groups are vascular plants.
• It is absent in non-vascular plants like mosses.

Last verified on 18-06-2026

Explanation

• Endoplasmic Reticulum (ER) and Golgi apparatus transport proteins.
• Rough ER helps in protein synthesis and initial transport.
• Golgi apparatus modifies, packages, and sends proteins.

Last verified on 18-06-2026

Explanation

• Mitochondria and chloroplasts contain their own DNA besides nucleus.
• They can reproduce independently to some extent.
• Mitochondrial DNA is inherited from the mother.
• Chloroplast DNA is found in plant cells.
• Both are semi-autonomous organelles.

Last verified on 18-06-2026

Explanation

• Chromosomes are made of DNA and proteins.
• DNA carries genetic information.
• Proteins (mainly histones) help package DNA.
• Together they form chromatin material.
• Chromosomes are found in the nucleus of cells.

Last verified on 18-06-2026