ব্যাংক নিয়োগ প্রস্তুতি ⎯ লং কোর্স

A sound unit is any acoustic unit of sound measurement.
dB, decibel - noise of sound measurement is called decibels (dB). Ratio of the sound pressure to reference pressure to something.
Sone - a unit of perceived loudness equal to the loudness of a 1000-hertz tone at 40 dB above threshold, starting with 1 sone.
Phon - a unit of subjective loudness.
Hz, hertz - unit of sound frequency is called hertz (Hz)

The lightest or least dense metal that is a pure element is lithium, which has a density of 0.534 g/cm³.
This makes lithium nearly half as dense as water, so if lithium was not so reactive, a chunk of the metal would float on water.

Water is a good solvent of ionic salts because it has a high dipole moment.
Salts are ionic compounds which, when dissolved in water, break up completely into ions.
They arise by the reaction of acids with bases, and they always contain either a metal cation or a cation derived from ammonium (NH₄+).

Sodium carbonate, Na₂CO₃, is also known as washing soda. It can remove temporary and permanent hardness from water. Sodium carbonate is soluble but calcium carbonate and magnesium carbonate are insoluble. The water is softened because it no longer contains dissolved calcium ions and magnesium ions.

Nitrous oxide, commonly known as laughing gas or nitrous, is a chemical compound, an oxide of nitrogen with the formula N₂O.
Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain reducing effects

Heavy water (deuterium oxide, ²H₂O, D₂O) is a form of water that contains only deuterium (2H or D, also known as heavy hydrogen) rather than the common hydrogen-1 isotope (1H or H, also called protium) that makes up most of the hydrogen in normal water.

Galvanisation is a process of coating ''Iron or Steel'' with Zinc to protect it from the Rusting.
Zinc ''weathers at a very slow rate'', so the coating protects the inner metal and provides it a very long life.
This process intact the steel with full strength and provide a more delightful appearance.
Zinc has a greater electronegativity than iron and provides a specific protection to the ''steel from the outer environment''.

Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body's ability to fight infection and disease.
HIV is a sexually transmitted infection (STI). It can also be spread by contact with infected blood or from mother to child during pregnancy, childbirth or breast-feeding. Without medication, it may take years before HIV weakens your immune system to the point that you have AIDS.
There's no cure for HIV/AIDS, but medications can dramatically slow the progression of the disease. These drugs have reduced AIDS deaths in many developed nations.