UPSC Civil Services GK Questions 2026

Doab, from the Persian words for two and water, is the name for the tract of land between two rivers.

The Purvanchal or Eastern Hills are the southward continuation of the Himalayas beyond the eastern bend of the Brahmaputra, and they are made up of the Patkai Bum, the Naga Hills, the Manipur Hills and the Mizo or Lushai Hills.

Majuli lies in the Brahmaputra in Assam and is counted the largest river island in the world. The Brahmaputra carries an enormous load of silt from a young, rapidly eroding basin, and because its channel is braided and shifts often, it has built large islands and sandbars called chars.

The Pir Panjal is the longest and most important range of the Lesser or Himachal Himalaya, running from the Jhelum through Jammu and Kashmir towards Himachal Pradesh and separating the Kashmir valley from the Jammu plains.

The Himalayas were raised when the northward-moving Indian plate collided with the Eurasian plate and the sediments of the shallow Tethys Sea between them were compressed into great folds and thrust upward.

Kanchenjunga rises to 8,586 metres on the Sikkim-Nepal border and is the highest peak in India's undisputed territory, as well as the third highest in the world after Everest and K2.

Nathu La lies in eastern Sikkim on the old trade route from Gangtok to Lhasa and is one of the passes on India's border with the Tibet region of China; Jelep La, also in Sikkim, is the other.

Bhangar is the older alluvial deposit of the Northern Plains. It forms terraces that stand above the present flood level, so fresh silt no longer reaches it, and long leaching has left calcareous concretions called kankar in its profile.

The Bhabar is a narrow belt about 8 to 16 kilometres wide, laid along the foot of the Shiwalik range, where the rivers leaving the hills drop their coarsest load.

Karewas are thick beds of glacial clay, silt and other lake sediments laid down in the Kashmir valley, which lies between the Pir Panjal and the Greater Himalaya.

Duns are flat-floored longitudinal valleys formed where rivers coming out of the Lesser Himalaya were held up behind the rising Shiwalik and filled the depression with gravel and silt.

The Himadri is the innermost and northernmost of the three parallel Himalayan ranges, with an average height of about 6,000 metres.

A lichen is a partnership of an alga and a fungus and takes its water and nutrients straight from the air, with no protective cuticle and no roots.

A catalytic converter holds platinum, palladium and rhodium on a honeycomb support, which oxidise carbon monoxide and unburnt hydrocarbons to carbon dioxide and water and reduce the oxides of nitrogen to nitrogen.

An electrostatic precipitator gives the dust and ash particles in the flue gas an electric charge as they pass an electrode, and then collects them on plates carrying the opposite charge; the plates are shaken so that the collected ash falls into a hopper.

This Act is the specific law on air pollution. It empowers the Central and State Pollution Control Boards to lay down emission standards for industry and for vehicles, to declare air pollution control areas and to require consent before a polluting plant is set up or operated.

The National Air Quality Index has six bands: 0 to 50 is Good, 51 to 100 Satisfactory, 101 to 200 Moderate, 201 to 300 Poor, 301 to 400 Very Poor and 401 to 500 Severe.

The Montreal Protocol, adopted in 1987 under the Vienna Convention, commits its parties to phasing out chlorofluorocarbons, halons and other chemicals that destroy stratospheric ozone, and it is regarded as the most successful environmental treaty for that reason.

Particulate matter is graded by the diameter of the particles measured in micrometres, so PM10 means particles of ten micrometres or less and PM2.5 means particles of 2.5 micrometres or less, which is about thirty times finer than a human hair.

Sulphur dioxide from industry and traffic around Agra is oxidised in the air and comes down as sulphuric acid, which attacks the calcium carbonate of marble.