Explanation

• SI stands for the International System of Units
• The world's standard modern metric system used for science, commerce, and everyday measurements.

The SI system is built upon seven fundamental base units: 

1. Metre (m) – for length
2. Kilogram (kg) – for mass
3. Second (s) – for time
4. Ampere (A) – for electric current
5. Kelvin (K) – for thermodynamic temperature
6. Mole (mol) – for amount of substance
7. Candela (cd) – for luminous intensity 

Last updated 27-07-2026 by NA

Explanation

• When tectonic plates slide past each other, they form faults or fault lines.
• This type of plate boundary is called a transform boundary.
• Movement along fault lines can cause earthquakes.
• A famous example is the San Andreas Fault in California, USA.

Last verified on 28-97-2026

Explanation

• A horst is an uplifted block of the Earth's crust formed between two parallel normal faults.
• It is created by tectonic forces during crustal extension.
• The adjacent blocks move downward, making the horst appear elevated.

Additional information:

• Graben: Down-faulted block between two normal faults
• Normal fault: Forms due to tensional forces
• Reverse fault: Forms due to compressional forces
• Strike-slip fault: Forms due to horizontal shearing forces

Last verified on 28-07-2026

Explanation

• Einstein's equation E=mc² shows that mass can be converted into energy and vice versa.
• c: Speed of light = 299,792,458 m/s (≈ 3×10⁸ m/s)
• E: Energy
• m: Mass
• It was proposed by Albert Einstein in 1905 as part of the Special Theory of Relativity.

Last verified on 28-07-2026

Explanation

• Lahore's smog is mainly caused by pollutants from vehicles reacting with sunlight.
• Nitrogen oxides (NOₓ) and volatile organic compounds (VOCs) form ground-level ozone and fine particles.
• Industrial emissions, crop residue burning, and brick kilns also worsen smog.
• Smog is most severe during the winter season (October–January).

Last verified on 27-07-2026