Mercury have the lowest melting point among metals.

A metallic bond is characterized by free electrons and generally forms a specific geometric pattern of compact arrangement of atoms. All metals (except mercury) thus exist in a solid state at room temperature and have a specific crystal structure. Mercury belongs to the zinc group of elements in the periodic table, which comprises zinc, cadmium and mercury. They all have completely filled-up atomic orbitals. It becomes difficult to knock out these electron(s) from their orbitals and form metallic bonds. Therefore, they are soft (low melting point) and do not show multiple valence states unlike other transitional or rare earth metals. In mercury, the binding energy of outer electrons (towards nucleus) is highest and no electron is available to participate in metallic bond formation. Therefore, mercury does not have a specific crystal structure and is the only metal which is liquid at room temperature with a melting point of -38 degree Celsius.

Distilled water doesn't conduct electricity..

Distilled water does — but very little compared to piped, well or salt water. The reason is that the way a liquid conducts electricity is by the positively or negatively charged ions that are actually moving from one of the electrodes to the other, carrying charge (electricity) with them. Salt water has salt in it, NaCl, which readily ionizes or dissociates to ions of Na+ and Clthat can float through the water carrying charge and thus conduct electricity. Distilled water is water that was boiled to steam and recondensed to water. So distilled water is relatively pure H2O. Water can ionize to H+ and OH- like salt does, but it ionizes to a far lesser degree and is very resistant to conducting electricity.

Orgin of +, - etc symbols...

The earliest print appearance of the modern signs seem to come from a book on Mercantile Arithmetic by Johannes Widmann in 1489, used to indicate surpluses and deficits. The + is a simplification of the Latin “et” (comparable to the ampersand - &). Widmann referred to the symbols - and + as minus and mer. According to the ‘Earliest Uses of Various Mathematical Symbols’ website, a book published by Henricus Grammateus in 1518 used the symbols. Robert Recorde, the designer of the equals sign, introduced plus and minus to the UK in 1557 in The Whetstone of Witte.

Mineral water contain...

Naturally available water, after having come in contact with various salts found in soil stratas and atmosphere, contains a large number of chemicals. Some of them are calcium, magnesium, potassium, sodium, iron, sulphates, nitrates, nitrites, phosphates and oxygen. Small quantities of these substances are responsible for the taste and odour of natural water and are useful for essential functioning of the human body. Very small quantities of copper, chromium, chlorine, fluorine, arsenic, lead, cadmium, mercury and selenium are also found, depending upon the chemistry of the soil.

sungrazer..

When comets break up, smaller comets and sungrazers are formed. As these approach the sun, they break into smaller fragments before colliding into it. Sungrazers are classified into families and the largest is the Kreutz family, with over 500 sungrazers. It was discovered by Heinrich Kreutz, a 19thcentury German astronomer who found that some sungrazers came from a larger comet that broke up 12,000 years ago.

"similia similibus curantur" ?

‘Similia similibus curantur’ is a phrase coined by Dr Samuel Hahnemann, the founder of homoeopathy. Nearly 180 years ago, he did an experiment with a drug decoction made from the bark of the chincona tree, known for its curative properties in the treatment of malaria. He drank the decoction, though he was healthy, and developed the symptoms of malaria. This made him believe that a drug which possesses the property of curing an ailment can create symptoms of the disease in a healthy person who takes the drug in large doses.

Jack of all trades means

‘Jack of all trades, master of none’ is a figure of speech used with reference to a person who is competent with many skills but is not outstanding in any particular one. The phrase was in common use during the 1600s and was used as a term of praise. ‘Jack’ in those days was a generic term for ‘man'. Later, the ‘master of none’ was added and the expression ceased to be flattering.

Zodiac signs named after Animals

The term ‘zodiac’ stands for animals. However, all zodiac signs do not represent animals, like Libra is represented by a balance. Astrologically and astronomically, zodiac signs are representative of various pattern formed by stars. Ancient astronomers had named each zodiac by the shape formed by a few important and bright stars resembling the shape of animals, located in that section of the sky.

February have 28 days, and July and August, 31 days...

According to a popular legend, July was named after Julius Caesar and hence it had 31 days. Later, when Augustus Caesar took over the Roman Empire, he wanted August, the month named after him, to have 31 days as well. Hence, the two extra days were taken from February, which was then left with 28 days. However, some historians don’t agree with this reasoning. They believe February always had 28 days ever since the time of King Numa Pompilius. He decided that a year would have 355 days, the length of 12 lunar cycles. Back then, even numbers were considered unlucky. So, he created seven months with 29 days, and four with 31. Since he now needed one short even-numbered month, he chose February, as it was considered the least favourite month for it arrived during the middle of winter. And hence, it was given only 28 days.

Hindi India’s national language..

Neither the Constitution nor the laws of India accord the status of national language to any language in India. Indian law states that no language will be made the national language unless and until all the constituent states of the Union of India accept it. Of the 28 states and seven Union Territories, only ten states and three Union Territories have Hindi as the principal official language. However, Article 343 of the Indian Constitution states that the official language of the Union (India) shall be Hindi in Devanagari script.

E-R diagram

The E-R diagram (entity-relation) is a diagrammatical representation of a data model based on a perception of the real world that consists of a collection of basic objects called entities and of relationships among these objects. It is widely used in database design. The E/R diagram was introduced by P P Chen. An entity is a tangible object that exists in the real world, about which some relevant information may be stored. The qualities of an entity which can be stored as information are called the attributes. For example, if teacher is an entity then the teacher’s ID, name, etc. are all its attributes. An association among several entities is called a relationship.

Bird that lives the longest.....

The British record is 68 years in the case of a female European eagle-owl which was still alive in 1899. Other records regarded as probably reliable include 73 years (1818-1891) for a Greater Sulphur-Crested Cockatoo, 72 years (1797-1869) for an African Grey Parrot, 70 years (1770-1840) for a Mute Swan and 69 years for a raven. In 1972, a southern Ostrich aged 62 years and 3 months was killed in the Ostrich Abattoir at Oudtshoorn, Cape Province, South Africa. Jimmy, a red and green Amazon Parrot owned by Bella Ludford of Liverpool, England was allegedly hatched in captivity on December 3, 1870 and lived for 104 years in his original brass cage, dying on January 5, 1975. On October 28, 1982 the death of London Zoo’s famous Greater Sulphur-Crested Cockatoo — Cocky — was reported, after spending 57 years in the parrot house. He was already a mature bird when he was acquired by R Stevens at the turn of the century, and was probably at least 40 years of age when he was presented to the zoo in 1925.

Denuclearisation...

Denuclearisation means states disposing of nuclear weaponry or power in their possession. It includes removal, banning, or eliminating nuclear weapons or nuclear power sources from a place, industry, or organisation.

World’s first post office...

Although the origins of the postal system date back to antiquity, the British Postal Museum claims the oldest functioning post office in the world is on High Street in Sanquhar, Scotland. According to the museum, this post office has functioned continuously since 1712 AD. Sanquhar is a quiet, insignificant town, but in its heyday, its residents included many influential aristocrats, who must have played a significant role in having the first post office located there. Those days, horses and stage coaches would carry mail.

Invention of the clock....

The earliest way of telling the time was by looking at the progress of the shadow cast by a twig stuck upright in the ground. Round about 1300 BC, this was developed by the inhabitants of ancient Egypt and Mesopotamia into the sundial. The sundial served for a thousand years until the invention of the clepsydra, or water clock. This was the first clock with moving parts. The mechanical clock was not invented until the 13th century and it was driven by weights. The spring-driven clock was invented sometime around 1450 AD.

Sponge iron...

Sponge iron is a metallic product formed by the reduction of iron ore at a temperature just below the fusion point of iron. This product is called sponge iron due to its porous nature. It is also called as direct reduced iron (DRI).

Who built the Eiffel Tower in Paris?

The Eiffel Tower, an immense structure of exposed latticework supports made of iron, was erected for the Paris Exposition of 1889. The Prince of Wales officiated at the ceremonial opening. Of the 700 proposals submitted in a design competition, one was unanimously chosen, a radical creation of the French structural engineer Alexandre Gustave Eiffel. He was assisted by engineers Maurice Koechlin and Emile Nouguier, and architect Stephen Sauvestre.

Computer keep record of the time even when it is shut down...

Our computers are not run by a single operating system, but also the BIOS (basic input output system) which resides permanently in the chips of the motherboard to which virtually every computer hardware is connected. The BIOS is kept powered by a button cell (1.5 V approximately) or any variant. The cell remains present on the board and helps the BIOS remember not only the time but other hardware settings as well. The GUI (graphical user interface) syncs with the BIOS time every the computer is booted up and hence shows the computer shows the correct time.

About encoder and decoder.

An encoder is a device which transforms the data into some bits known only to it and the decoder is a device which transforms those coded bits to generate the original data again. These two are mainly used in computer technology but the underlying concept can be used anywhere. For example, the name ‘Delhi’ can be coded as ‘ihleD’ or ‘45#1278’. Later, the decoder regenerates the original ‘Delhi’ from this code as it knows the coding scheme.

... devised the sign language used by the hearing impaired.

Jerome Cardan devised the sign language. Deaf and mute people faced unreasonable brutality at one point of time. Jerome Cardan was an Italian doctor who believed that the mute and deaf people could be taught to communicate by using written characters. Finger characters were worked out for them in the seventeenth century which was very similar to the present-day finger alphabets. About seventy five years ago the deaf were taught to communicate ideas almost entirely by means of signs, facial expressions and finger alphabets.