Explanation

• Wilhelm Conrad Rontgen discovered X-rays
• He was discovered on 8 November 1895.
• He got the Nobel Prize in Physics in 1901.

Additional questions

• The penetrating power of X-rays depends on their frequency

Last updated 26-07-2026 by NA

Explanation

• 24-karat (24K) gold is considered the "best"
• Purity: 99.9% pure gold.
• Color: Rich, deep, bright yellow.

Additional information

• 22K Gold: 91.7% pure gold. It is mixed with harder metals like silver or copper.
• 18K Gold: 75% pure gold. It is highly durable and excellent for diamond settings 
• Carat is the unit of measurement for the physical weight of diamonds/gold.

Last updated by NA on 16-07-2026

Explanation

• Chemical Name: Acetic Acid (Ethanoic Acid)
• Chemical Formula: CH₃COOH
• Vinegar Concentration: 4–8% Acetic Acid
• Type of Acid: Weak Organic Acid
• Uses: Food seasoning, pickling, preservation, cleaning

Last verified on 10-07-2026

Explanation

• Carbon dioxide (CO₂) is used in fire extinguishers.
• It extinguishes fire by displacing oxygen and cooling the burning material.
• CO₂ fire extinguishers are especially effective for electrical and flammable liquid fires.
• Carbon dioxide is a colorless and non-flammable gas.
• It leaves no residue after use.

Last verified on 09-07-2026

Explanation

• Sound cannot travel through a vacuum because there are no particles to carry sound vibrations.
• Sound needs a medium such as a solid, liquid, or gas to travel.
• Since space is nearly a vacuum, sound cannot be heard there.
• The speed of sound in a vacuum is 0 m/s.

Additional information:

• Infrasound: Below 20 Hz
• Audible sound: 20 Hz – 20,000 Hz (20 kHz)
• Ultrasound: Above 20 kHz
• Speed of sound in air: 343 m/s
• Speed of sound in water: 1,481 m/s

Last verified on 07-06-2026

Explanation

• Vitamin D is essential for healthy bones.
• Its deficiency leads to Rickets in children and Osteomalacia in adults.
• Sunlight is the best natural source of Vitamin D.

Additional information:

Deficiency effects:

• Bone pain
• Weak bones
• Skeletal deformities

Other Vitamin Deficiencies:

• Vitamin A: Night blindness
• Vitamin C: Scurvy
• Vitamin B7 (Biotin): Hair fall

Last verified on 17-01-2026

Explanation

• Vitamin K helps to make various proteins that are needed for blood clotting and the building of bones.
• Prothrombin is a vitamin K-dependent protein directly involved with blood clotting.

• Vitamin C may protect the body against the effects of pollution.
• It may also prevent blood clots and reduce bruising.

Last verified on 31-03-2026

Explanation

• Solids → fastest sound speed
• Liquids → medium speed
• Gases → slowest speed

Steel is more elastic and dense.

• Steel ≈ 5000 m/s
• Air ≈ 332 m/s
• Water ≈ 1500 m/s

Last verified on 11-04-2026

Explanation

• Rainfall is measured using a Rain Gauge.
• It collects rainwater and measures it in millimeters (mm).
• Widely used in weather forecasting and meteorology.
• Helps in studying climate and agriculture patterns.

Last verified on 31-03-2026

Explanation

• A carbon microphone does not depend on the magnetic effect of current.
• Based on the variation of electrical resistance
• It converts sound vibrations into electrical signals 

Additional information 

Devices like electromagnets, electric bells, and ammeters work due to the magnetic effect of current.

Last updated on 09-03-2026