RRB Group D GK Questions 2026

In 1798 Cavendish used a delicate torsion balance to measure the extremely small attraction between lead spheres in a laboratory and from it obtained a value of G, about 6.674 times ten to the power minus eleven newton metre squared per kilogram squared.

A mercury barometer balances the pressure of the atmosphere against a column of mercury, which stands about 76 centimetres high at sea level.

Weight equals mass times the acceleration due to gravity, and the acceleration due to gravity on the moon is about one-sixth of its value on the earth because the moon has a much smaller mass and a smaller radius.

It states that a body immersed wholly or partly in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced, so the apparent loss in weight of the body equals the weight of the displaced fluid.

Pascal's law states that pressure applied to an enclosed fluid is transmitted undiminished in every direction to all parts of the fluid and to the walls of the container.

Escape velocity is the minimum speed a body must be given so that it leaves the gravitational pull of the planet and never returns.

The earth is flattened at the poles, so the distance from the centre is least there, and since g varies inversely as the square of that distance, g is largest at the poles.

Pressure is thrust per unit area, so its unit is one newton per square metre, and this unit is named the pascal after Blaise Pascal.

Sambhar Lake lies west of Jaipur in Rajasthan, has no outlet to the sea and loses water only by evaporation, so salts brought in by seasonal streams accumulate in it.

The Montreux Record names sites already on the Ramsar list where the ecological character has changed, is changing or is likely to change because of pollution, drainage, encroachment or other human interference.

Designated in 2008 in Gujarat, it covers the largest area of any biosphere reserve in India, taking in the marine national park and sanctuary of the gulf together with its islands, coral reefs, mangroves and mudflats, which support corals, dugongs, dolphins and large numbers of migratory shorebirds.

The core zone is the innermost and the only strictly protected part of a biosphere reserve, usually already notified as a national park or a wildlife sanctuary.

Both were placed on the Ramsar list in 1981 and were the first Indian wetlands to be so recognised.

The United Nations Educational, Scientific and Cultural Organization launched the Man and the Biosphere Programme in 1971 as an intergovernmental scientific programme to improve the relationship between people and their environment, and the sites recognised under it form the World Network of Biosphere Reserves.

Loktak, in Manipur, is the largest freshwater lake of north-east India, and its surface carries phumdis, thick floating mats of vegetation, soil and organic matter that rise and fall with the water level.

The Nilgiri Biosphere Reserve, spread across Tamil Nadu, Kerala and Karnataka in the Western Ghats, was designated in 1986 as the first biosphere reserve of India, and in 2000 it also became the first Indian reserve to be included in the UNESCO World Network of Biosphere Reserves.

The Ramsar Convention was signed on 2 February 1971, and that anniversary is observed each year as World Wetlands Day to draw attention to the services wetlands provide, such as flood control, groundwater recharge, water purification and habitat for migratory birds.

The Convention on Wetlands of International Importance was signed on 2 February 1971 in the Iranian city of Ramsar, on the shore of the Caspian Sea, which gave the treaty its popular name.

The polar easterlies blow out of the high pressure belts over the poles towards the sub-polar low pressure belts, so they carry extremely cold and dry air.

Ustad Bismillah Khan was the shehnai player who lifted that instrument from wedding processions to the concert stage.