RRB ALP GK Questions 2026

A p-type semiconductor is made by adding a trivalent impurity such as boron, aluminium, gallium or indium.

An n-type semiconductor is made by doping with a pentavalent element, that is one with five valence electrons, such as phosphorus, arsenic, antimony or bismuth.

A semiconductor has a small forbidden energy gap, so heating supplies thermal energy that pushes more electrons from the valence band into the conduction band, creating more electron-hole pairs.

UPI was launched by NPCI in 2016 as a system that lets a user link several bank accounts to one mobile application and transfer money instantly using a virtual payment address or a QR code, without sharing account numbers.

NavIC is the operational name of the system formally called the Indian Regional Navigation Satellite System, built by ISRO so that the country would not depend on a foreign constellation for positioning in a crisis.

The 802.15 family covers wireless personal area networks, the very short-range links meant to join the devices a single person carries, and Bluetooth was standardised within it as IEEE 802.15.1.

An accelerometer measures acceleration along three axes, which includes the constant pull of gravity, so the phone can work out which way is down and therefore how it is being held.

NFC is deliberately designed for extremely short range, so the two devices must be touching or nearly touching before any data passes.

GSM is the European-born digital standard that replaced the analogue first generation networks; it introduced the removable SIM card, digital encryption of the radio link, international roaming and the short message service, on which a plain text message is limited to one hundred and sixty characters.

Android uses a modified Linux kernel at its lowest layer to manage memory, processes, power and device drivers, and builds its own runtime, libraries, application framework and user interface above it.

The International Mobile Equipment Identity is a fifteen-digit number assigned to every handset, made up of a code identifying the type approval of the model, a serial part and a final check digit.

The SIM is a small smart card issued by the operator that stores the subscriber identity, the authentication keys used to prove that identity to the network, and a limited amount of contact and message data.

A telephone conversation requires both parties to speak and listen at the same time, so a mobile link must carry traffic in both directions together.

LTE is the radio access technology of fourth generation mobile networks, standardised by the Third Generation Partnership Project.

Thomas Graham found in 1833 that a light gas spreads through a porous partition faster than a heavy one, and that the rates of two gases are in the inverse ratio of the square roots of their densities, and therefore of their molar masses.

At ordinary atmospheric pressure carbon dioxide has no liquid stage: the solid passes straight into vapour at about minus 78.5 degrees Celsius.

In a liquid the resistance to flow comes mainly from the attraction between neighbouring molecules. Heating gives the molecules energy to slip past one another, so the attraction matters less and the liquid thins; hot honey and warm engine oil pour far more easily than cold.

Evaporation is a surface phenomenon in which the fastest-moving molecules of a liquid break free. Doing so needs the latent heat of vaporisation, and that energy is drawn from the liquid left behind and from whatever the liquid touches, so both grow cooler.

This is the heat one gram of ice at 0 degrees Celsius must absorb to become one gram of water at 0 degrees Celsius; the temperature does not rise at all while it melts, because the energy goes into breaking the hydrogen-bonded lattice.

Bromine is a dark reddish-brown, dense, fuming liquid at ordinary room temperature, with a melting point of about minus 7 degrees Celsius and a boiling point of about 59 degrees Celsius.