Explanation

• Light Year is the distance that light can travel in one year.
• The distance light travels in one year is known as light year.
• 1 light year is equal to 9.5 x 10¹²km.

Last verified on 30-03-2026

Explanation

• Sir Isaac Newton formulated the Three Laws of Motion.
• He presented them in 1687 in his famous work Principia Mathematica.

Three Laws of Motion:

1. First Law — Law of Inertia: An object remains at rest or in uniform motion unless acted upon by an external force.
2. Second Law — Law of Acceleration: The net force on an object is related to its mass and acceleration.
3. Third Law — Action and Reaction: For every action, there is an equal and opposite reaction.

Last verified on 05-09-2026

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

• 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

The chemical name for quartz is silicon dioxide

Chemical Formula: SiO₂

Composition: Silicon (Si) and Oxygen (O)

Structure: A framework of silicon-oxygen tetrahedra

Common Names: Silica, Rock Crystal (for the clear variety)

Explanation

Steel is most elastic among the rubber, steel, glass and sponge.

Steel having the most steep linear stress-strain curve among all.

A stiffer material will have a higher elastic modulus.

Explanation

salt (NaCl), sodium chloride, a mineral substance of great importance to human and animal health, as well as to industry. 

Formula: NaCl

Molar mass: 58.44 g/mol

Melting point: 801 °C

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ND30-12-2022

ND5-07-2023

Explanation

Acid rain is mainly caused by emissions of Sulfur dioxide and Nitrogen oxide in the atmosphere.

Acid rain mainly Causes health problem like Asthma.

Explanation

Explanation

Light year refers to speed of light expressed in miles per year

(it is about ten trillion kilometers or six trillion miles).

Light year is a unit of distance.

Light Year: the distance that light can travel in one year. 

The distance light travels in one year is known as the light year.