Explanation

• The age of Earth’s oldest rocks is commonly determined using the Uranium-238 → Lead-206 radioactive decay system.
• Uranium-238 decays very slowly over billions of years.
• This long half-life makes it ideal for dating ancient geological materials.
• It helps scientists estimate Earth’s age (~4.5 billion years).

Last verified on 14-06-2026

Explanation

• Butter melts faster than ghee.
• Because it contains more water and milk solids, making its structure less stable.
• Water in butter lowers its melting stability at room temperature.
• This makes butter softer and quicker to melt.

Additional information:

• Ghee is almost pure fat with no water content.
• Ghee remains more stable because it is more refined.

Last verified on 14-06-2026

Explanation

• Zinc is commonly used in toothpaste.
• Because it helps reduce bacterial growth and controls bad breath.
• Zinc compounds (like zinc citrate or zinc chloride) kill or inhibit oral bacteria.
• It also helps reduce plaque formation.
• This improves overall oral hygiene.

Last verified on 14-06-2026

Explanation

• Soap lathers better in soft water because hard water contains calcium (Ca²⁺) and magnesium (Mg²⁺) ions that react with soap to form insoluble salts.
• These salts reduce soap’s ability to produce foam.
• Soft water does not contain these ions, so soap works fully.
• More soap remains active in soft water for lather formation.

Last verified on 14-06-2026

Explanation

• Sedimentary rocks favor the formation and storage of petroleum.
• Petroleum forms from organic matter buried under sediments over millions of years.
• These rocks have porous spaces where oil and gas can accumulate.
• Common examples include sandstone and limestone.

Last verified on 14-06-2026

Explanation

• Type: Chemical compound
• Formula: H₂O
• Elements: Hydrogen + Oxygen
• Bond: Covalent bond
• Ratio: 2 hydrogen : 1 oxygen

Last verified on 10-06-2026

Explanation

• Chlorine has the smallest atomic radius among the given elements.
• Atomic radius decreases from left to right across a period.
• Period 3 elements: Sodium (Na), Magnesium (Mg), Aluminum (Al), Chlorine (Cl)
• Atomic radius trend: Na > Mg > Al > Cl
• Reason: Increasing nuclear charge across the period

Last verified 10-06-2026

Explanation

• Ibn Zakariya Al-Razi is considered the father of Pediatrics (Child healthcare).
• He was a famous Muslim physician, philosopher, and scientist.
• Field: Medicine, Chemistry, Philosophy
• Known as: Rhazes
• Famous books: Al-Hawi, Kitab al-Mansuri

Last verified on 09-06-2026

Explanation

Hydrogen gas is H₂, molar mass ≈ 2.016 g/mol  

Moles = mass / molar mass  

= 8.064 g / 2.016 g/mol = 4.0 mol

So there are 4 moles of H₂ molecules.

Last verified on 09-06-2026

Explanation

• Iron (Fe) is a trace element required in very small amounts in the body.
• It is essential for forming hemoglobin in blood.
• It helps in oxygen transport in red blood cells.
• Other trace elements include: Zinc, Copper, Iodine, Manganese, Cobalt.

Last verified on 09-06-2026