Explanation

• Black Gold: Petroleum (Crude Oil)
• Color: Dark black / brownish black
• Main Uses: Fuel, petrol, diesel, kerosene, plastics
• Importance: Backbone of modern industry and transport

Additional information:

• Top Oil-Producing Countries:
  1. Saudi Arabia
  2. USA
  3. Russia
  4. Iraq
  5. Iran

Last verified on 16-06-2026

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

• Safety goggles are used to protect eyes in the laboratory.
• They protect from chemicals, splashes, dust, and harmful particles.
• They are an essential part of lab safety equipment.

Last verified on 16-06-2026

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