Questions

An electric arc is a visible plasma discharge between two electrodes that is caused by electrical current ionizing gasses in the air. Electric arcs occur in nature in the form of lightning.

The world's largest silver producer is Mexico.

A price floor is the minimum price that can be charged. A binding price floor occurs when the government sets a required price on goods at a price above equilibrium. Because the government requires that prices not drop below this price, that price binds the market for that good.

A binding price ceiling is one that is set below equilibrium price.

Foreign keys are the columns of a table that points to the primary key of another table. They act as a cross-reference between tables.

In detail : A Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. In simpler words, the foreign key is defined in a second table, but it refers to the primary key or a unique key in the first table.

Nicolaus Copernicus was decribed by his work on "The Heliocentric Theory" which is based on that the earth revolves around the Sun.

This theory was developed in parts by different astronomers over many years, namely Aristarchus, Copernicus, Kepler, and Galileo.