RRB Group D GK Questions 2026

Water erosion passes through stages, and the soil lost grows at every stage. Splash erosion, numbered II, is the first and mildest: raindrops strike bare soil and knock single particles a few centimetres away.

Overgrazing strips the protective cover of grass, loosens the surface with hooves and leaves bare soil exposed to rain and wind, so it is one of the leading causes of soil erosion in dry India, never a remedy.

Bad lands are stretches of land cut into a close network of deep gullies and sharp ridges, so dissected that cultivation becomes impossible, and they are produced when running water removes the topsoil through sheet wash that concentrates first into rills and then into gullies.

Bose designed the crescograph to magnify the growth of a plant many thousand times and record it on a smoked glass plate, which allowed him to show that plants respond to light, heat, touch and other stimuli in ways that resemble responses in animals.

A seismograph holds a heavy mass that tends to stay still while the ground and the frame of the instrument move during a tremor; the relative motion is magnified and traced as a seismogram, from which the arrival times of the primary, secondary and surface waves are read.

In 1895, while working with a discharge tube, Roentgen found an unknown radiation that passed through cardboard and flesh but was stopped by bone and metal, and made a screen coated with a fluorescent salt glow.

In 1928 Fleming noticed that a mould of the genus Penicillium which had contaminated a culture plate in his London laboratory had killed the staphylococcus bacteria around it, and he named the active substance penicillin.

A fathometer, also called an echo sounder, sends a pulse of sound from the hull of a ship to the sea floor and times the returning echo; since the speed of sound in sea water is known, the time gives the depth.

A lactometer is a floating instrument that measures the relative density of milk. Pure milk has a density slightly greater than that of water, so adding water lowers the reading and the float sinks deeper, which is how dilution is detected.

A barometer measures the pressure of the atmosphere, and the mercury barometer invented by Evangelista Torricelli in 1643 does so by balancing the weight of the air against a column of mercury about 76 centimetres high at sea level.

Elektron is the Greek name for amber, the fossilised tree resin which the ancient Greeks found would attract straw, feathers and bits of dust after being rubbed with fur.

Working independently in the 1830s, Michael Faraday in England and Joseph Henry in the United States showed that a changing magnetic flux through a circuit sets up an electromotive force in it, and that the effect depends on the rate of change of flux rather than on the flux itself.

In 1932 Chadwick bombarded beryllium with alpha particles and showed that the highly penetrating radiation given off consisted of neutral particles with almost the same mass as a proton.

In 1897 Thomson passed an electric discharge through a gas at very low pressure and showed that the cathode rays produced were a stream of identical negatively charged particles, far lighter than any atom and the same whatever gas or electrode was used.

The princely states were not a small fringe of the map. Standard accounts place their share at roughly two-fifths of the land area of the subcontinent, and some put it close to a half, with around a quarter of the population; about 565 states of every size, from Hyderabad and…

It made Sikkim the twenty-second state of the Union after a referendum in which its people voted to end the rule of the Chogyal and to join India.

These were the former princely units and unions of states, among them Hyderabad, Mysore, Rajasthan, Saurashtra, Madhya Bharat, Travancore-Cochin, PEPSU and Jammu and Kashmir, and each was headed by a Rajpramukh rather than by a Governor.

It was formed in 1948 by grouping Patiala with Kapurthala, Jind, Nabha, Faridkot, Malerkotla, Nalagarh and Kalsia, with the Maharaja of Patiala as Rajpramukh, and it became a Part B state under the Constitution of 1950.

The Nawab of Junagadh, Mahabat Khan III, announced accession to Pakistan in September 1947 although his small state in Kathiawar was surrounded by Indian territory and had a largely Hindu population.

The Act let paramountcy lapse with effect from 15 August 1947, so in strict law every princely state became free either to accede to India, to accede to Pakistan, or to attempt to remain outside both.