Explanation

• Mercury is the only elemental metal that at room temperature is Liquid.
• Mercury (Hg) is the only metal that remains liquid at room temperature (about 25°C).

Additional information:

• Chemical Symbol: Hg
• Atomic Number: 80
• Melting Point: −38.83°C
• Boiling Point: 356.73°C

Last verified on 20-07-2026

Explanation

• Carbon Dating is one of the methods to calculate the age of fossils. It is based on the principle of Radioactivity.
• Radioactive isotope: Carbon-14 (¹⁴C)
• Half-life: 5,730 years
• Developed by: Willard Libby
• Introduced: 1949
• Dating range: Up to 50,000 years

Last verified on 20-07-2026

Explanation

• Noble gases are called inert gases because their outermost electron shell is complete.
• They are located in Group 18 of the periodic table.
• Due to their stable electronic configuration, they show very little chemical reactivity.
• Noble gases are colorless, odorless, and monoatomic under normal conditions.
• They are used in neon signs, electric bulbs, lasers, welding, and balloons (helium).

Last verified on 19-07-2026

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

Given ratio = Nitrogen : Sulphur : Phosphorus = 5 : 3 : 2  

Total parts = 5 + 3 + 2 = 10  

Total weight = 200 kg  

Value of 1 part = Total weight / Total parts  

= 200 / 10 = 20 kg  

Initial weight of Nitrogen = 5 x 20 = 100 kg  

Initial weight of Sulphur = 3 x 20 = 60 kg  

Initial weight of Phosphorus = 2 x 20 = 40 kg  

100 kg of Nitrogen is added.  

New weight of Nitrogen = 100 + 100 = 200 kg  

Verified & Updated