Explanation

• The SI unit of sound intensity is watt per square meter (W/m²).
• Sound intensity is the amount of sound power passing through a unit area.
• It shows how strong or weak a sound wave is at a particular point.
• Sound intensity decreases as the distance from the source increases.
• Decibel (dB) is used to measure sound intensity level, not the actual intensity

Last verified on 20-07-2026

Explanation

• Pakistan's standard household electricity supply is 220–240 V AC at 50 Hz.
• The frequency of alternating current (AC) is 50 cycles per second (50 Hz).
• This standard is used for homes, schools, offices, and most electrical appliances in Pakistan.

Last verified on 19-07-2026

Explanation

• Gregor Mendel is known as the Father of Genetics.
• He discovered the Laws of Inheritance through experiments on pea plants between 1856–1863.
• His research was published in 1866.

Last verified on 19-07-2026

Explanation

• Noble gases are called inert gases because their outermost electron shell is complete.
• They are located in Group 18 of the periodic table.
• Due to their stable electronic configuration, they show very little chemical reactivity.
• Noble gases are colorless, odorless, and monoatomic under normal conditions.
• They are used in neon signs, electric bulbs, lasers, welding, and balloons (helium).

Last verified on 19-07-2026

Explanation

• In 1924, Louis de Broglie proposed that matter has both particle and wave properties.
• This concept is known as the De Broglie Hypothesis or Matter Wave Theory.
• It became one of the foundations of Quantum Mechanics.

Last verified on 19-07-2026

Explanation

• The Universe is continuously expanding.
• Age of the Universe: ≈13.8 billion years
• Big Bang: ≈13.8 billion years ago
• Hubble's discovery: 1929
• Cosmic Microwave Background discovered: 1965
• Expansion is accelerating due to dark energy.

Last verified on 19-07-2026

Explanation

• The reciprocal of bulk modulus is called compressibility.
• Formula: Compressibility = 1 / Bulk Modulus
• Bulk modulus measures resistance to compression.
• Symbol: β = 1/K.
• SI unit: Pa⁻¹ (per Pascal).
• Higher bulk modulus means lower compressibility

Last updated 18-07-2026 by NA

Explanation

• Bones do not secrete hormones,
• Hormones are produced by glands in the endocrine system.
• The parathyroid gland secretes parathyroid hormone.
• It regulates calcium levels in the blood and bones.

Addition information 

• Functions performed by bones in the human body:
• Support: Provides a rigid framework for soft tissues.
• Protection: Shields vital organs like the brain, heart, and lungs.

Last updated 18-07-2026 by NA

Explanation

• The SI unit of electric current is Ampere (A).
• Electric current measures the flow of electric charge.
• Defined using the elementary charge (e = 1.602176634 × 10⁻¹⁹ C).
• Named after: André-Marie Ampère (scientist).
• 1 Ampere = 1 Coulomb per second (1 A = 1 C/s).

Last verified on 08-06-2026

Explanation

• The lungs are located in the thoracic cavity.
• The thoracic cavity is the chest cavity protected by the rib cage.
• It contains the lungs, heart, trachea, and major blood vessels.
• The lungs are enclosed by the pleural membranes.
• This cavity plays a vital role in breathing and respiration.

Last verified on 18-07-2026