Explanation

• A Barometer is an instrument used to measure air (atmospheric) pressure.
• It helps in weather forecasting by measuring changes in atmospheric pressure.
• The mercury barometer is the oldest type of barometer.
• It was invented by Evangelista Torricelli in 1643.
• Barometers are widely used in meteorology and aviation.

Last verified on 09-07-2026

Explanation

Explanation

• The SI unit of force is the newton (N).
• 1 N = the force needed to accelerate 1 kg of mass by 1 m/s²
• Derived unit: N = kg·m/s²
• Named after Sir Isaac Newton
• Based on F = ma (Newton's second law)

Additional information:

1. The metre, unit of length — symbol m
2. The kilogram, unit of mass — symbol kg
3. The second, unit of time — symbol s

Last verified on 09-11-2026

Explanation

• Calcium (Ca) is an alkaline earth metal belonging to Group 2 of the periodic table.
• Its atomic number is 20.
• Mercury (Hg) is a liquid metal at room temperature.
• Its atomic number is 80.
• Mercury has a boiling point of approximately 356.7°C.

Last verified on 09-11-2026

Explanation

• Battery is a device that converts chemical energy into electrical energy.
• Batteries work by using a galvanic cell.
• It is an electrochemical device made up of two electrodes and an electrolyte solution.

Last verified on 16-03-2026

Explanation

• Atoms of the same element with different numbers of neutrons are called isotopes.
• Atoms of the same element have the same number of protons and electrons but different numbers of neutrons.

Last verified on 09-11-2026

Explanation

• The instrument used to measure temperature is called a thermometer.
• A thermometer shows how hot or cold an object or place is.

Additional information:

• Barometer measures air pressure.
• Hygrometer measures humidity (moisture in air).

Last verified on 16-06-2026

Explanation

• White blood cells (leukocytes) are part of the immune system.
• They play a key role in defending the body against infections, diseases, and foreign invaders.
• They help maintain overall health.

Last verified on 09-11-2026

Explanation

• Chlorine is commonly used to disinfect drinking water.
• It kills harmful bacteria and many other microorganisms.
• This process is called chlorination.

Last updated 08 Nov 2026 by NA

Explanation

Earth's Rotation 

• - Sidereal Day: Approximately 23 hours, 56 minutes, 4 seconds.
• - Meaning: The time Earth takes to rotate once relative to distant stars.
• - Solar Day: Approximately 24 hours, measured from one noon to the next.
• - Difference: About 4 minutes.

Last updated 08 Nov 2026 by NA