RRB NTPC GK Questions 2026

The layered structure of graphite can accept lithium ions between its sheets, a process called intercalation, and release them again without breaking down, which is what makes the cell rechargeable over hundreds of cycles.

Whittingham built the first working lithium cell in the 1970s, Goodenough found that a lithium cobalt oxide cathode could give a far higher voltage, and Yoshino replaced the dangerous metallic lithium anode with a carbon material, producing the safe, rechargeable cell that was commercialised in 1991.

A BEV carries no engine at all; it runs entirely on a traction battery that is charged from an external electricity supply, and it has no tailpipe emissions.

This is a glucose analogue in which fluorine-18 replaces a hydroxyl group.

It regulates the use of pre-natal diagnostic techniques, requires every ultrasound clinic to be registered and to keep records, and prohibits sex selection before or after conception as well as the communication of the sex of the foetus to anyone.

Gadolinium is a rare earth element whose ion is strongly paramagnetic, so it shortens the relaxation time of nearby hydrogen nuclei and brightens the tissue it reaches.

Hounsfield, an engineer at EMI in Britain, built the first clinical CT scanner, and Cormack, a physicist, had independently worked out the mathematics of reconstructing a cross-section from measurements taken along many directions.

When sound is reflected from a moving target, the frequency of the echo is shifted: higher when the blood is moving towards the probe and lower when it is moving away.

Certain crystals develop a voltage across their faces when they are mechanically squeezed, and conversely change shape when a voltage is applied.

The tesla is the SI unit of magnetic flux density, and clinical MRI scanners commonly work at one and a half or three tesla, produced by a superconducting coil kept cold by liquid helium.

A single proton, the nucleus of ordinary hydrogen, has a spin and therefore a magnetic moment, and hydrogen is by far the most abundant such nucleus in the body because the body is largely water and fat.

The cutoff or minimum wavelength of the continuous X-ray spectrum arises when an electron gives up its entire kinetic energy in a single collision with the target.

The Hounsfield unit, named after Godfrey Hounsfield, expresses how strongly a small volume of tissue attenuates X-rays, on a scale fixed by definition at zero for water and minus one thousand for air.

MRI works by placing the hydrogen nuclei of the body in a strong static magnetic field and disturbing them with radiofrequency pulses, which lie in the harmless low-energy part of the electromagnetic spectrum.

Working with a discharge tube at the University of Wurzburg in November 1895, Roentgen noticed that a screen coated with a fluorescent salt glowed even when the tube was covered, and he traced the effect to an unknown penetrating radiation that he called X-radiation.

The 2011 Census recorded a literacy rate of 86.05 per cent for Chandigarh, well above the national figure of about 73 per cent, which is to be expected of a territory that is almost entirely urban and has a large service and education sector.

The territory returns a single member to the Lok Sabha from the Chandigarh constituency.

The Open Hand, a large metal sculpture mounted so that it turns with the wind, stands in the Capitol Complex and was conceived by the architect as a sign of a hand open to give and open to receive, that is, open to new ideas.

It was formed by damming the Sukhna Choe, a seasonal stream descending from the Shivalik hills, as part of the city plan, and it is fed by rain rather than by a perennial river.

The city's sectors are numbered in sequence, but the number thirteen was deliberately left out because it is widely regarded as unlucky, so the numbering jumps from Sector 12 to Sector 14.