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  

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Explanation

• Neon is the primary gas used in decorative and advertising lights
• The color of the light depends on the gas in the tube.

Additional information

• Argon: Produces a blue or (mixed with mercury) green/purple light.
• Helium: Glows yellow or pink.
• Krypton: Emits a whitish-yellow light.
• Xenon: Creates a violet/lavender light.

Last updated by NA on 16-07-2026

Explanation

Let the original weight of the solution = x kg

Acid present in original solution = 92% of x = 0.92x kg

Water is added. Only water is added, so the amount of acid remains the same.

Final weight of solution = 40 kg  

Final concentration of acid = 84%  

Acid present in final solution = 84% of 40 = 0.84 x 40 = 33.6 kg

Since acid remains the same:  

0.92x = 33.6  

x = 33.6 / 0.92  

x = 36.52 kg (approx)

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Explanation

• Enzymes are protein-based chemical compounds produced in the cells of living organisms.
• They act as biological catalysts, speeding up chemical reactions.
• Enzymes are essential for digestion, metabolism, and energy production.

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Explanation

• C₄H₆O most likely belongs to the Aldehyde or Ketone class.
• The formula indicates two degrees of unsaturation, which can include a carbonyl group (C=O).
• Aldehydes and ketones commonly contain this functional group.

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Explanation

Moles needed = 0.5 × 0.1 = 0.05 mol

Molar mass of CaCl₂ = 111 g/mol

Required mass = 0.05 × 111 = 5.55 g

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