5th Class

The modern flame thrower was not particularly innovative—it simply launched burning fuel to spread fire. However, when used on the battlefield, its effect was devastating, and it is remembered as the most demoralizing infantry weapon ever used. At the turn of the twentieth century, German inventor Richard Fiedler experimented with two types of flame thrower. The Flammenwerfer was a smaller, handheld weapon that used pressurized gas to push out streams of burning oil. The larger model was not as portable, but had a range of 118 feet (36 m) and could produce a continuous stream for forty seconds. When used in warfare, the weapons were highly dangerous, both for the enemy and the users, as the pressurized gas cylinders were prone to explosion. Modern flame throwers consist of a backpack containing a tank with a flammable liquid, often napalm, and a tank with compressed gas. When fired the pressurized gas more...

"Your bath took care of the past, but for future freshness, make Mum your next step." Mum advertisement, 1946 The development of the roll-on deodorant is a perfect example of how ingenious lateral thinking can link one seemingly unrelated invention to another and result in a useful product. "Mum" deodorant—first developed in the late nineteenth century—was a rather sticky, hard-to-apply substance. When Helen Barnett Diserens (1918-2008) joined the product team of Bristol-Myers as a researcher in the late 1940s, one of the company's skills' was working creatively on a select list of consumer-Bqsed toiletries. A member of Diserens's team suggested that she take a look at another recent marvel, the ballpoint pen (actually based on an idea from the late 1800s) to get some inspiration for improving Mum's applicator. Diserens's new roller applicator—made of glass with a rolling ball at its tip—was tested in the United States in 1952. After more...

"A mathematician is a device for turning coffee into theorems." Albert Einstein, scientist The cultivation of the coffee bean can be traced back to tenth-century Ethiopia. It was introduced to Europe in the sixteenth century and the Americas in the mid- 1600s, after which it proved an extremely popular beverage. But preparing it correctly, brewed from ground coffee beans, could be time-consuming. It was not until 1901 that a Japanese-American chemist named Satori Kato, using an earlier process he pioneered for making instant tea, created the world's first soluble instant coffee. Kato's coffee, which he called "Sanka," though initially bitter and pungent, was a concentrated solution made from coffee beans and water that was dehydrated leaving a powdery residue, which dissolves easily in hot water. While living in Guatemala in 1909, Belgian-born chemist George C. Washington was the first to market mass-produced coffee with his "Red E Coffee" brand, after more...

Dr. Rajendra Prasad, a statesman and social worker, was the first President of the Republic of India. He was a great  educationist and a man of world fame. He was an author too. Dr. Rajendra Prasad was born on 3rd December, 1884 at Saran District in Bihar. His educational career was very bright. He stood first in the Entrance Examination of Kolkata University in 1902. He also stood first in M.A. and L.L.B. Examinations. After passing Law he started his practice at Patna High Court. His practice was very roaring and he achieved a great success as a lawyer. He earned a lot by his practice, but he always spent a considerable part of his income on the welfare of people. He was married to Rajbansi Devi, who was also a very simple lady. The atmosphere of the village where he was brought up was very simple. Far away from more...

India is a land of the largest democracy. There is a multi party system of governance. As per the constitutional provision the party with the highest majority through a general election is entitled to form the government and its leader will be the Prime Minister of India. After getting Independence in 1947 the Congress Party which played the leading role in the struggle for freedom emerged as the ruling party in India. This party continued to rule till 1977 continuously. In due course India was over crowded with so many political parties that the people were largely confused. In 1977 the Janata Party—a unified power of opposition parties replaced the long ruling party i.e. the Congress. But only for a few years. For the first time in 1989 the politics of coalition took a new form in Indian political system. Coalition means an alliance of different political parties which come more...

“To see barges waiting ...at a lock affords a fine lesson in how easily the world may be taken." Robert Louis Stevenson, An Inland Voyage (1878) Locks interrupt a canal or river with stepped stretches of still water, thus reducing currents in the waterway and conserving deep water for passage. The forerunner of today's lock was the flash lock, already in use by the first century B.C.E. in China, whereby part of a dam would be temporarily opened to allow passage of a vessel. Those traveling downstream were carried on the resulting surge of water, whereas those sailing in the opposite direction hauled the vessel against the torrent. Such an arrangement was dangerous and resulted in the loss of large quantities of water downstream for every vessel passing, a circumstance not appreciated by mill owners reliant on the supply. In 984, during the construction of China's Grand Canal, engineer Qiao more...

Obedience is a great virtue. The lesson of obedience is an important one. It may be both personal and social. It is a great moral virtue and a sure sign of refined personality. Obedience is at the root of the progress of this world. Our parents love us. They wish our good. They always work for our welfare. They are glad if we are great and good. Whatever they bid us to do is for our own good. We should obey them and do what they wish us to do. The young in a family are expected to follow the advice of their elders. If they refuse to obey, the institution of the family ceases to exist. Now what starts well at home shows better in the society. For, home is the breeding ground of the values of life. An obedient child learns to respect his teachers, obeys the rules more...

There can be few people who have not encountered this remarkable product. Assumed by some to have been a spin-off from wartime, military technology, and therefore named "War Department—1940," the title actually relates to the number of attempts it took the inventors of this water displacing (WD) chemical to perfect the product. It was at a lab in San Diego, California, in 1953, that the Rocket Chemical Company and its three personnel embarked on their mission to create a range of rust- prevention and degreasing products for use in the aerospace industry. After thirty-nine "almosts," they succeeded. The aerospace contractor Convair bought the chemical for use as a corrosion inhibitor on its Atlas missiles, and other wholesale orders soon followed. Rocket Chemical Company employees had for some time been taking small amounts of the petrochemical-based product home for their personal use. Company founder and chemist Norm Larsen (1923-1970), suspecting that more...

"Wrong and inappropriate use has caused LSD to become my problem child." Albert Hofmann Lysergic acid diethylamide (LSD) is a powerful psychedelic drug. While now commonly associated with 1960s dropout youth culture, it was heralded as a wonder drug in the 1940s and 1950s and was used to treat thousands of psychiatric patients. Swiss chemist Albert Hofmann (1906-2008) first synthesized LSD in 1938, expecting it to be useful as a medicinal stimulant. In 1943 he returned to studying it and after experiencing some pleasant sensations while working with the drug. .he took a dose of 0.25 mg. Hofmann bicycled home and began to experience its psychedelic effects, the world's first "trip." He reported that the morning after he felt entirely renewed and that his senses were "vibrating in a condition of highest sensitivity." Today LSD is mainly taken as a recreational drug for its psychological effects. Common accounts are of more...

Scoring tips The following tips would certainly help you in scoring well in the exam: Go through previous years’ question papers along with solutions, and analyse the subject pattern and focus on those subjects which have maximum weightage. Books can further be divided into two categories: Books that deal with the fundamentals and focus on conceptual clarity. Here textbooks by reputed publishers are a must. Books that provide a great deal of difficult and time-consuming questions and are used essentially as practice material. Do not rely on just one book for a topic; instead consult a couple of books for the same topic. Prepare notes after completing each chapter. Practise the maximum number of questions possible on a given topic. This certainly strengthens your preparation. Keep in mind that those topics which are not in GATE syllabus could be certainly left out. Make a list of topics in which you more...