Questions

In the given options, "His stomach rumbled like an approaching train" is an example of Simile.

All the other options are examples of metaphors. 

Simile and Metaphor are both figure of speeches in English which are used for comparing things but the only difference is Simile uses LIKE or AS words in comparing and metaphor directly compares without using any words.

It is WATER.

A skid happens whenever the tires lose their grip on the road. Braking skids occur when the brakes are applied so hard that the front or rear wheels lose traction.

The seven elements — helium, neon, argon, krypton, xenon, radon, and oganesson of Group 18 of the periodic table are Noble or Inert gases.

Radon is the heaviest and Helium is the lightest gases of the noble gases.

Southern Democrats are members of the U.S. Democratic Party who reside in the South. All the above given were the part of agenda of southern democrats.

Using fear and violence for political gain is the part of the agenda of southern democrats most directly affected African American.

Facilitate means assist someone in their progress or work. Here Help is the only word which is similar in meaning with facilitate. Halt and check are antonyms i.e opposite in meaning of facilitate. 

Hence, facilitate is similar in meaning to help.

Karst is a type of landscape that is characterized by caverns, caves, sinkholes, and underground streams. These features were all caused by erosion of the underlying rock.

Limestone type of rock usually underlies a karst landscape.