SSC CHSL GK Questions 2026

Dry air is about seventy-eight per cent nitrogen by volume, which makes the atmosphere the great reservoir of the nitrogen cycle, yet the triple bond of the nitrogen molecule is so strong that plants and animals cannot use the gas directly and depend on fixation.

Denitrification is the reduction of nitrate to nitrogen gas, which escapes to the atmosphere and completes the nitrogen cycle; it is carried out by these bacteria in waterlogged soils where oxygen is scarce, and it is the reason farmers lose nitrogen from flooded fields.

Nitrification happens in two stages, and the first is the oxidation of ammonia to nitrite by chemoautotrophic bacteria of the genera Nitrosomonas and Nitrococcus.

Rhizobium is a bacterium that lives in a symbiotic relationship with legumes such as gram, pea, bean, groundnut and arhar, forming nodules on their roots in which it converts nitrogen gas into ammonia using the enzyme nitrogenase; this is why legumes are grown in rotation to restore soil nitrogen.

Phosphorus has no stable gaseous compound in nature, so its reservoir is rock, chiefly the mineral apatite; it enters the soil only through slow weathering, passes through plants and animals, and returns to sediments, which makes it a purely sedimentary cycle and the slowest of the common cycles.

Humus is the dark, formless material left in soil after decomposers have broken down dead leaves, roots and animal remains; it resists further microbial attack and decays only very slowly, which makes it the long term store of carbon and nutrients in soil and a key step in every biogeochemical…

TIFRAC, the Tata Institute of Fundamental Research Automatic Calculator, was the first computer designed and built within India; it was commissioned in 1960 and Jawaharlal Nehru gave it that name.

In his report on the EDVAC design in 1945 John von Neumann set out a computer in which a single memory holds both the program and the data it works on, with a control unit, an arithmetic and logic unit and input and output; that layout is still called the…

Herman Hollerith built an electric tabulating machine that read holes punched in cards, and it cut the time needed to process the United States census of 1890 from years to months.

In 1936 the British mathematician Alan Turing described an abstract machine, now called the Turing machine, that defines what it means for a problem to be computable, and in 1950 he proposed the Turing test, by which a machine is judged intelligent if its answers cannot be told from a…

Intel released the 4004 in 1971, putting a complete central processing unit on a single chip for the first time and beginning the fourth generation of computers along with the age of the personal computer.

The Scottish mathematician John Napier published his work on logarithms in 1614, which turned multiplication into addition, and he then devised a set of numbered rods, Napier’s bones, with which products could be read off mechanically.

ENIAC, the Electronic Numerical Integrator and Computer, was completed in 1946 at the University of Pennsylvania by J. Presper Eckert and John Mauchly and used some eighteen thousand vacuum tubes; it was a first generation machine, filled a large room and consumed a great deal of power.

Ada Lovelace, the daughter of Lord Byron, worked with Charles Babbage on the Analytical Engine, and the notes she published in 1843 include a step by step sequence for computing Bernoulli numbers on it, which is recognised as the first computer program; a programming language, Ada, is named after her.

The French mathematician Blaise Pascal built the Pascaline in 1642 to help his father with tax calculations; it worked with toothed wheels and could add and subtract, and the programming language Pascal is named in his honour.

Babbage designed the Difference Engine in 1822 and then the Analytical Engine, a general purpose mechanical computer with a store for numbers, a mill for arithmetic, punched card input and printed output, which is the plan of a modern computer drawn a century before one could be built; for that…

The IBM System/360, announced in 1964, was built around integrated circuits, and the integrated circuit is exactly what defines the third generation of computers; the series is also remembered for introducing a single compatible family of machines of different sizes.

The generations of computers are named for the switching device they use, and the second generation, running from the late 1950s into the early 1960s, replaced the bulky vacuum tube with the transistor, which had been invented at Bell Laboratories in 1947.

The Ministry of AYUSH was created on 9 November 2014 by upgrading the existing department, so that the traditional systems of medicine would have a ministry and a minister of their own.

These three are the Brihat Trayi, the great triad of Ayurvedic literature: Charaka on internal medicine, Sushruta on surgery and Vagbhata summarising both in the Ashtanga Hridaya.