RedCastle Resources interview questions

Questions regarding concepts of GIS, database, & Programming: (1) What is projection and geographic coordination vs projected coordination system? (2) What's a foreign key in the database? (3) Difference between Null & 0? (4) Difference between an interface & abstract class? (5) What's "this" keyword in OOP? (6) Difference between function overloading and overriding? (7) Difference between HTML & HTML5? (8) Three main ways to apply CSS styles to a web page? (9) Difference between Pass by value & pass by reference? (10) Difference between raster, vector data? (11) What's variable hoisting in JavaScript? (12) What's SQL join?