UPSC Civil Services GK Questions 2026

Bleaching powder is prepared by passing chlorine over dry slaked lime and is written as calcium oxychloride; in water it releases chlorine, which kills bacteria and other pathogens, and that is why it is used both for disinfecting water supplies and for bleaching cloth and paper.

Alum, that is aluminium sulphate or potash alum, is a coagulant: in water it forms a gelatinous hydroxide that gathers the fine clay and colloidal particles into heavier flocs, which then settle in the sedimentation tank and are removed, leaving clear water for filtration.

Water contracts as it is cooled to four degrees, is densest at that temperature, and then expands again as it cools further to zero, which is called the anomalous expansion of water.

These bicarbonates are formed when water containing dissolved carbon dioxide passes over limestone, and they are unstable; on boiling they lose carbon dioxide and settle as insoluble carbonates, which is why this kind of hardness is called temporary and can be removed by boiling alone, or by the Clark method…

Heavy water is D2O, in which both hydrogen atoms are deuterium, the isotope whose nucleus has one proton and one neutron, so its molecular mass is twenty instead of eighteen.

In an ion exchange plant the water passes through a cation resin, which takes up the calcium and magnesium ions, and then through an anion resin, which takes up the sulphate, chloride and bicarbonate ions; because the hardness-causing ions are actually taken out of the water, the hardness can be…

A bench of five judges decided it in 2022 and upheld the Constitution (One Hundred and Third Amendment) Act, 2019, which provides up to ten per cent reservation for the economically weaker sections, by a majority of three to two.

It reserves seats in the House of the People, that is the Lok Sabha, for the Scheduled Castes and the Scheduled Tribes, the number being in proportion to their population; there is no reservation of seats for the Other Backward Classes in Parliament.

It empowers the President to appoint a commission to investigate the conditions of socially and educationally backward classes, the difficulties they face and the steps that should be taken to remove them, and both the Kalelkar Commission of 1953 and the Mandal Commission of 1979 were appointed under it.

The first Backward Classes Commission was appointed in 1953 under Article 340 with Kaka Saheb Kalelkar as its chairman, and it submitted its report in 1955; the report was not acted upon because its criteria for identifying backwardness were considered vague.

The Constitution (One Hundred and Second Amendment) Act, 2018 inserted Article 338B, which makes the National Commission for Backward Classes a constitutional body with the duty to investigate and monitor the safeguards provided to the socially and educationally backward classes; the same amendment added Article 342A for the central list…

It amended Article 16(4A) so that a government servant of the Scheduled Castes or Scheduled Tribes promoted under the reservation also keeps the seniority of the promoted post, which is called consequential seniority, and the change was given effect from 1995.

It was passed after the Supreme Court in State of Madras v. Champakam Dorairajan struck down a communal order reserving seats in colleges, holding that it offended Article 15(1); Parliament answered by adding clause (4) to Article 15, which permits special provision for the advancement of socially and educationally backward…

The nine-judge bench in Indra Sawhney upheld the twenty-seven per cent quota for the Other Backward Classes but held that the socially advanced members of those classes, described as the creamy layer, must be excluded so that the benefit reaches the genuinely backward; the same judgment laid down the fifty…

The 103rd Amendment Act of 2019 added clause (6) to Article 15 for reservation in admission to educational institutions and clause (6) to Article 16 for reservation in appointments, in each case up to ten per cent for the economically weaker sections of citizens who are not covered by the…

It says that nothing in Article 16 shall prevent the State from making any provision for the reservation of appointments or posts in favour of any backward class of citizens which, in the opinion of the State, is not adequately represented in the services under the State.

The Second Backward Classes Commission was appointed in 1979 under Article 340 of the Constitution, which empowers the President to appoint a commission to investigate the conditions of socially and educationally backward classes.

As Director-General of the Archaeological Survey of India, John Marshall carried out long excavations at Taxila from 1913 onwards and published a detailed account of the city's successive settlements; the site was later inscribed on the UNESCO World Heritage List in 1980.

Ikhtiyaruddin Muhammad bin Bakhtiyar Khalji, a commander in the service of the Ghurids, overran Bihar at the end of the twelfth and the beginning of the thirteenth century and destroyed the monastic universities of the region, after which organised Buddhist learning in eastern India came to an end.

Later Tibetan accounts call the library of Nalanda Dharmaganja, the treasury of the law, and say that it consisted of three buildings named Ratnasagara, Ratnodadhi and Ratnaranjaka, the tallest of which is described as a nine-storeyed structure.