Defence GK Questions 2026

Hydrofluorocarbons were adopted as substitutes for chlorofluorocarbons in refrigeration and air conditioning because they do not harm the ozone layer, but they turned out to be very powerful greenhouse gases, so the Kigali Amendment of 2016 brought them under the Montreal Protocol with a schedule for reducing their use.

The day marks the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987 and is observed every year with a theme announced by the United Nations.

Marble is calcium carbonate, and sulphur dioxide in polluted air, along with the sulphuric acid of acid rain, reacts with it to form calcium sulphate, so the stone loses its shine, turns yellow and becomes pitted and flaky.

These gases come from burning coal and oil in thermal power stations, smelters and vehicles, are oxidised in the atmosphere and dissolve in water droplets to form sulphuric acid and nitric acid, which come down as acid rain.

The Montreal Protocol was adopted in 1987 under the Vienna Convention of 1985 and sets the timetable by which countries must stop producing and using chlorofluorocarbons, halons, carbon tetrachloride, methyl chloroform and methyl bromide.

The Dobson unit, named after the scientist who built the instrument for measuring atmospheric ozone, expresses how thick the ozone column would be if all of it were brought down to the surface at standard temperature and pressure; a hundred Dobson units correspond to a layer one millimetre thick.

About nine tenths of the atmosphere's ozone lies in the stratosphere, roughly fifteen to thirty five kilometres above the surface, where ultraviolet rays split oxygen molecules and the free atoms combine with other oxygen molecules to make ozone.

Nitric oxide and nitrogen dioxide, together written as nitrogen oxides, are air pollutants that come mainly from combustion in vehicles and power stations; they help form smog and acid rain but are not counted among the greenhouse gases of the natural atmosphere.

A primary pollutant is released directly from a source, while a secondary pollutant is formed in the atmosphere when primary pollutants react.

Each of the other three statements is correct on its own, which is exactly why the combined option is the answer.

Khandesh was ruled by the Faruqi dynasty, which set itself up in the Tapi valley in the late fourteenth century independently of the Bahmanis, and it was annexed by Akbar in 1601; it never formed part of the Bahmani kingdom and so did not emerge from its break-up.

Mahmud Gawan, the Persian-born wazir of Muhammad Shah III who held the title Malik-ut-Tujjar, built a madrasa at Bidar in 1472.

Abdur Razzaq was sent by Shah Rukh, the Timurid ruler of Herat, and reached Vijayanagara in 1443, when Deva Raya II of the Sangama dynasty was on the throne.

Amuktamalyada is a Telugu poem on the life of the Tamil saint Andal that also sets out the duties of a king, and it was composed by Krishnadevaraya himself, which is why he is remembered as a poet-king with the title Andhra Bhoja.

On 26 January 1565 the combined armies of the Deccan sultanates of Bijapur, Ahmadnagar, Golconda and Bidar defeated the Vijayanagara forces led by Aliya Rama Raya at Talikota, a battle also named Rakshasi-Tangadi after two nearby villages.

In 1425 Ahmad Shah Wali moved the Bahmani capital from Gulbarga to Bidar, which he renamed Muhammadabad, and Bidar remained the seat of the kingdom until it broke up.

Humayun Shah Bahmani ruled from 1458 to 1461 and the chronicles of the Deccan record his punishments as so savage that he was nicknamed Zalim, the cruel or the tyrant.

Krishnadevaraya of the Tuluva dynasty ruled from 1509 to 1529 and his reign is treated as the golden age of Vijayanagara: the Raichur doab was won back, Odisha's Gajapati ruler was humbled, Telugu literature flourished under the eight court poets called the Ashtadiggajas, and the Vitthalaswamy and Hazara Rama temples…

Harihara I and Bukka Raya I, the sons of Sangama, founded the city and the empire of Vijayanagara in 1336 on the southern bank of the Tungabhadra, at the site now known as Hampi in Karnataka.

In 1347 the centurion nobles of Daulatabad, the Amiran-i-Sadah, rebelled against the Delhi Sultan and raised one of their own, Hasan Gangu, to the throne of the Deccan.