Questions

Concatenation of text means adding a word with other word. It can be done using Ampersand (&).

For example :

'Amper' & 'sand' = Ampersand 

1. US Navy commissioned world’s largest aircraft carrier, USS Gerald R Ford into the fleet. The commissioning ceremony was held at Naval Station Norfolk, Virginia in presence of US President Donald Trump.

2. USS Gerald R. Ford is the first ship in this new class of nuclear-powered aircraft carriers for the U.S. Navy. The ship is named after the 38th President of the United States Gerald Ford and has been built by Newport News Ship Building Company. The massive 1,106-foot-long carrier is powered by two new generation nuclear reactors.

A karst topography is that which composes of limestone and its associated features and structures. Karst topography and caves develop in limestone rocks due to their solubility in dilute acidic groundwater. The solubility of limestone in water and weak acid solutions leads to karst landscapes.

Flowing rivers, can be found in areas away from karst topography.

RADAR - RAdio Detection And Ranging.

A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. 

Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain.

Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.