Explanation

• Al-Biruni was a famous Muslim mathematician, astronomer, and geographer.
• He calculated the Earth's radius using trigonometric principles and measurements of the angle of dip from a mountain.
• His estimated radius was approximately 6,339.6 km, which was remarkably close to the modern mean radius of about 6,371 km.
• He lived from 973 CE to 1048 CE.

Last verified on 09-11-2026

Explanation

• Sir James Chadwick discovered the neutron in 1932.
• He was a British physicist.
• His discovery completed the basic picture of the atomic nucleus.
• He received the Nobel Prize in Physics in 1935 for this discovery.

Additional information:

• J. J. Thomson – Electron (1897)
• Ernest Rutherford – Atomic nucleus (1911) and Proton (1917)

Last updated by NA on 05-11-2026

Explanation

• Alexander Graham Bell is credited as the inventor of the telephone.
• He was awarded the first successful patent for it.
• The telephone was invented in 1876.
• Bell made the first-ever telephone call to his assistant Thomas Watson.

Last updated by NA on 06-11-2026

Explanation

• Stayed for 14 days at Quba during the migration to Madinah in 1 AH (622 CE).
• Stayed at the house of Hazrat Kulthum bin al-Hidm (رضي الله عنه).
• Laid the foundation of Masjid Quba, the first mosque in Islam.

Last updated by NA on 05-11-2026

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 by NA on 05-11-2026