Explanation

• The hardness of water is mainly caused by the presence of calcium (Ca²⁺) and magnesium (Mg²⁺) ions.
• These ions react with soap and reduce its ability to form foam.
• Hard water commonly contains dissolved salts of calcium and magnesium.
• Temporary hardness is mainly due to bicarbonates.
• Permanent hardness is due to sulfates and chlorides.
• Water hardness is measured in terms of calcium carbonate (CaCO₃) equivalent.

Last verified on 14-06-2026

Explanation

• Fluorine (F₂) is the strongest oxidizing agent among the halogens.
• It has the highest tendency to gain electrons due to its high electronegativity.
• Oxidizing power decreases down the halogen group.
• The order is: F₂ > Cl₂ > Br₂ > I₂.
• Fluorine reacts very easily with other elements.

Last verified on 14-06-2026

Explanation

• The most abundant mineral in Earth’s mantle is Olivine.
• It dominates the upper mantle, especially in the form of peridotite rocks.
• Olivine is rich in magnesium and iron.
• It forms under high pressure and temperature conditions.

Last verified on 14-06-2026

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