RRB Group D GK Questions 2026

Silver reacts with traces of hydrogen sulphide in the air and forms a black coating of silver sulphide. This slow attack on a metal by its surroundings is called corrosion, and on silver it is usually called tarnishing.

In uniform circular motion the acceleration points towards the centre of the circle, at right angles to the velocity. In uniform circular motion the speed stays the same, but the direction of motion changes at every point, so the velocity keeps changing and the body is accelerating.

Villi are tiny finger-like folds of the inner lining of the small intestine that greatly increase its surface for absorbing digested food.

Zinc oxide is amphoteric: it reacts with acids as a base and with strong alkalis as an acid, giving a salt and water in both cases.

Slaked lime on the wall slowly absorbs carbon dioxide from the air and turns into a thin, shiny layer of calcium carbonate.

The ABO system sorts blood by the antigens present on the surface of red blood cells, and it has exactly these four groups.

Seen from the east end, the current flows away from the observer, and by the right-hand thumb rule the field lines around it are clockwise circles in a plane perpendicular to the wire.

The Eastern Railway zone of Indian Railways has its headquarters at Fairlie Place in Kolkata. Eastern Railway was formed in 1952 out of the East Indian Railway, one of the oldest railway companies in India, whose first train in the east ran from Howrah to Hooghly in 1854.

When an object is weighed under water, the water pushes up on it with a buoyant force, so it seems lighter than in air; this reduced reading is its apparent weight.

Bleaching powder is calcium oxychloride, CaOCl₂, and DDT is dichlorodiphenyltrichloroethane; chlorine is the one element common to both. Bleaching powder is made by passing chlorine gas over dry slaked lime.

The more a colour is slowed by glass, the higher the refractive index for it and the more it bends.

The filament of an incandescent bulb must glow white-hot without melting, and tungsten has the highest melting point of all metals, about 3,400 °C. An incandescent bulb works by the heating effect of electric current: the thin coiled filament gets so hot, around 2,500 °C or more, that it gives…

In a given medium under the same conditions, sounds of all frequencies travel at the same speed; the speed depends on the medium, not on the pitch.

Light travels fastest in a vacuum; in any material medium, including carbon disulphide, it slows down, so its speed there (X) is less than its speed in vacuum (Y).

The bulb of a headlight is placed at the principal focus of a concave mirror, so the reflected light leaves as a strong beam of parallel rays that reaches far down the road.

Turmeric is a natural indicator: soap is basic and turns the yellow stain reddish brown, and rinsing with plenty of water removes the soap so the stain turns yellow again.

Thrust is a force and impulse is force multiplied by time, so thrust divided by impulse has the unit 1/second (s⁻¹), which is the unit of frequency.

The cochlea of the inner ear changes the pressure variations of sound into electrical (nerve) signals, which the auditory nerve then carries to the brain.

In glass, light of shorter wavelength travels more slowly, so the glass has a higher refractive index for it and bends it more.

A system whose walls let no heat pass in or out is called adiabatic, so any change in its state happens with zero heat exchange (Q = 0).